Denver voters may have chosen two of the more centrist contenders for the mayoral runoff, but that doesn’t mean Mike Johnston and Kelly Brough are mirror images of one another.

In the next six weeks, key distinctions are likely to emerge between the well-funded candidates — as will new endorsements, consolidated coalitions and fine-tuned campaign messages that together will determine which one becomes Denver’s 46th mayor.

Though several self-identified progressive candidates failed to make the June 6 runoff, including third-place Lisa Calderón, their voters could determine the outcome. That is among the big X-factors that experienced Denver political operatives and observers say give both Brough and Johnston viable paths to victory.

“I think it’s a mistake to assume they are identical,” said City Councilwoman Robin Kniech, who’s finishing up her third and final term as an at-large member and has stayed neutral in the race. “We need to look more closely at these two candidates.”

The people doing that looking potentially include not only voters who opted for the 14 other candidates in the crowded April 4 election, but also the nearly two-thirds of registered voters who didn’t turn out. While turnout rarely increases substantially in Denver’s runoffs, that is among the uncertainties at play.

So is the role of identity politics in an open mayoral runoff that, for the first time in more than 40 years, has no Hispanic or Black candidate — but also holds the possibility of electing the first woman as mayor.

Voting for mayor is about more than finding the best policy match. For many, it’s also about a candidate’s vision for the city, their trustworthiness and their authenticity, however those are judged.

“Both are experienced. Both are very dynamic in terms of their grasp of their issues,” said Jeff Fard, a Five Points activist known as Brother Jeff who voted for Calderón in the first round. “And so I think they have to convince someone like myself, who doesn’t have a candidate right now.”

In the first round, Johnston, a former state senator and leader of Gary Community Ventures, finished first with 24.5% of votes. Brough, a former city official and leader of the Denver Metro Chamber of Commerce, captured 20%. An outright majority was needed to avoid a runoff, and both fell far short.

Each has earned a big endorsement from a former mayor since then, with Federico Peña backing Johnston and Wellington Webb supporting Brough after previously endorsing state Rep. Leslie Herod, one of the progressives, in the first round.

The lower-placing candidates come from a broad spectrum, and both runoff contenders have been courting them. Calderón, who won 18.2% of the vote, so far has said publicly that she’s focused on helping progressive candidates win several City Council district runoffs — leaving it unclear if she’ll make an endorsement; her campaign manager, Sarah Lake, declined to comment on her behalf.

On Monday morning, after this story was published, Herod joined Johnston at a news conference in Civic Center to endorse him. She came in fifth in the first election, receiving 10.7% of votes. Earlier, 10th-place finisher Thomas Wolf, who netted 1% of votes, endorsed Brough.

An attempt to reach state Sen. Chris Hansen (who was sixth, at 4.8%) wasn’t successful. But others, including Councilwoman Debbie Ortega, who came in seventh (at 4.5%), and eighth-place Ean Thomas Tafoya (1.6%) say they may weigh in.

“I definitely want to make sure the interests that are important to my supporters are referenced and addressed by the candidates,” said Tafoya, an environmental justice activist. He expressed hope that others, including Calderón, would not pass up a “huge opportunity to really leverage policy” by negotiating an endorsement.

The fourth-place finisher, Andy Rougeot, a self-funder who won nearly 12% of the vote as the only Republican-affiliated candidate, has made his intentions clear to The Denver Post.

“I will not be endorsing either candidate,” Rougeot said in a statement. “I don’t believe either Mike Johnston or Kelly Brough will do what’s needed to keep our city safe by adding police officers and aggressively enforcing the camping ban.”

That leaves it up to the candidates to attract Rougeot’s voters — though Kniech was among observers who said appealing to his supporters by taking an even harder line on crime or homelessness may put off the vast majority of Denver voters who are left-leaning.

Johnston has momentum. Could Brough make history?

The runoff candidates emerged from the first round with well-honed pitches and evidence of some strengths with voters.

Johnston, 48, has the momentum of finishing first. He’s run an energetic campaign animated by the vision of making Denver the country’s best city, drawing on nearly eight years of legislative experience and work spearheading initiatives such as Proposition 123, a state affordable housing funding mandate that Colorado voters approved last fall. He’s also leaned on ties he built within the city’s Black community as a legislator representing northeast neighborhoods.

As ballots were counted this month, his vote share held steady, reflecting strength both among early-voting older voters and the younger and more ethnically diverse electorate that turned in ballots on Election Day. He finished first in precincts in several pockets spread around the city, while finishing second to Herod in several precincts in predominantly Black neighborhoods.

Brough, 59, carries the potential of making history, a prospect buoyed by the five women candidates in the first round winning nearly 54% combined. She’s run a campaign focused on both a compelling personal story — including humble beginnings and hardship — and on the nuts and bolts of governing. She’s leaned heavily on her executive experience, including in city government, where she rose to then-Mayor John Hickenlooper’s chief of staff in late 2006, and then a dozen years as the Chamber of Commerce’s president and CEO.

She performed well among older voters and those who returned their ballots ahead of Election Day, with her vote share declining as later ballots were counted. Her strongholds were mostly in southeast Denver, though she finished second to Johnston in many well-heeled neighborhoods and occasionally was second to other candidates in more conservative-leaning or low-income areas.

Michael Dino, a longtime Democratic strategist, sees a thematic alignment in the endorsements from Peña, who served from 1983 to 1991, and his successor, Webb, who served through 2003. (Hickenlooper, now a U.S. senator, has suggested he won’t issue an endorsement, and neither has outgoing Mayor Michael Hancock.)

“Mike Johnston certainly has a bit of Federico Peña in him, in terms of the vision and laying out what he thinks Denver can be,” Dino said. Brough, for her part, “has a lot of the traits that (Webb) possessed, in terms of strong administrative skills, good executive experience and experience working in the city.”

The question is which approach voters will favor this year, he said.

Broader debate — and more scrutiny on candidates

Kniech predicts a broader debate in the runoff that moves well beyond the so-far prevailing issues — homelessness, housing affordability, and crime and public safety, all ranking among Denver’s knottiest problems — that dominated the first round’s debates and forums. She also expects there will be far more scrutiny on each candidate’s experience, background and past positions.

“I don’t think we had a close look at either of them,” she said, given how much competing attention there was in the first round.

For Johnston, that means closer looks at a legislative record that includes major liberal victories, such as a bill providing in-state tuition for undocumented students in Colorado. But he also took divisive stands as a leader on education reform, which has alienated some educators and teacher’s unions during his previous unsuccessful runs for governor and U.S. senator.

And for Brough, it means more attention to the positions taken by the Chamber of Commerce while she led it. Some were pro-business stands that she says didn’t reflect her personal opinions, including against paid family leave, while in other cases, she pushed the chamber to support gay rights and other liberal-leaning causes.

This will all play out during a longer runoff campaign than usual, thanks to Denver moving up the first-round election by a month. The runoff period now lasts nine weeks instead of four, and voters will receive their mail ballots the week of May 15.

Some analysts suggested the longer runoff could blunt Johnston’s momentum, but Camilo Vilaseca, his campaign manager, is optimistic.

“I feel like we’re in a pretty strong spot right now,” he said, “and are moving in the right direction in building the coalitions that historically have been important in winning mayor’s races” — including by working on appeals to different types of progressive voters.

His counterpart in Brough’s campaign agrees that Johnston started the runoff in a stronger position — though it has much to do with Johnston having twice as much outside spending backing him, including from several donors who have written six-figure checks.

“We’re the underdog, but we are ready,” said Sheila MacDonald, who also ran Jamie Giellis’ unsuccessful campaign against Hancock four years ago. “We’re running a grassroots effort here, and that means being with neighbors. That means going door to door. That means coffees across the city (and) in living rooms.”

TV ads soon will return, though Vilaseca says the campaigns may struggle to replenish their coffers because of the $500-per-individual-donor limit they accepted as part of the city’s new Fair Elections Fund donor match program.

Those limits don’t reset in the runoff, though the Denver Elections Division says it is granting Brough $187,500 and Johnston $153,385 as their runoff distributions from the matching program. Each runoff candidate receives 25% of what they earned in matching funds in the first round.

By all accounts, the rich backers who flooded independent-expenditure committees with money on each candidate’s behalf — $2.2 million has been reported for Johnston so far and $1.1 million for Brough — are reloading for more.

That outside money, and where it comes from, likely will continue to come under scrutiny, several political observers say.

Poll suggests Johnston is making inroads

The only public poll released so far suggested the candidates are in a tight race that’s within the margin of error, though Johnston came in at 39% to Brough’s 34% in a model weighted to slightly more conservative turnout than the April 4 election. That could understate Johnston’s support, his backers say.

The poll’s cross-tabs show that so far, Johnston is having an easier time attracting liberal voters than Brough. The candidates are more even with moderates, while Brough appeals more to conservative-leaners — a smaller piece of Denver’s pie.

“Voters who might have voted for Lisa Calderón or Leslie Herod — I don’t know how they’ll break, but I can imagine some of Mike’s (record) being appealing to them,” said Paul Teske, dean of the University of Colorado Denver’s School of Public Affairs.

But he’s among longtime political observers in Denver who caution that local politics is harder to predict, and voters of different stripes don’t always do what’s expected of them. While Brough’s business ties make her vulnerable, Teske said, Johnston’s recent history of being a “professional politician” by running for several offices might turn some voters off.

How to address homelessness, public safety or addiction “are not left-right issues, and I don’t think they necessarily think they play to the strengths of someone who is making a play for the far left,” said Alan Salazar, Hancock’s current chief of staff. “That said, it would be crazy not to acknowledge that there is a left orientation with a significant number of Denver voters.”

Tafoya says he thinks those voters will show up and make a choice in the runoff. But there are some conflicting signals, with Councilwoman Candi CdeBaca, who’s facing her own runoff in District 10, saying she urges progressive voters to focus on electing progressives to the City Council, even if it means skipping the mayor’s race.

Reaching progressives may require some attention to policy, said Wendy Howell, the state director of the Colorado Working Families Party.

“What they are looking for is people who are actually speaking to the solutions that they know work,” she said. That includes housing plans that have the city address the affordability gap by intervening more in the housing market, she said, and safety plans that address the root causes of crime rather than relying simply on hiring more police officers.

For now, it’s no guarantee that turnout will hold steady in the runoff. In past mayoral runoffs in recent decades, it’s been just as likely to decrease as increase.

Four years ago, Hancock and Giellis — both seen as moderates in a six-way race — made the runoff, leaving Calderón, the strongest liberal, in third place that time, too.

Ultimately, nearly 21,000 fewer voters participated in the runoff compared to the first round, with a small share of voters taking the option to sit out the second round.