In the final hours before Denver’s mayoral election, not much is clearer than it was a month ago.

Millions of dollars have been spent by the campaigns and their outside supporters. Dozens of forums and debates have given the 16 active contenders a chance to differentiate themselves. They’ve touted loads of endorsements.

Yet as the first-round election approaches on Tuesday, no clear frontrunners have emerged to leave the rest of the field in their dust. Undecided voters still seem to make up the largest bloc, as evidenced by the glacial pace of ballot returns. Less than 14% of mail ballots had been returned as of Friday, according to the Denver Elections Division.

“People are looking for a standout candidate, and they’re looking for a reason to vote,” said James Mejía, a Denver civic leader, former city official and mayoral candidate in 2011. “This one has thrown people for a loop. It’s unprecedented in Denver history in so many ways.”

The large field, a function of both the first open race for mayor in 12 years and a new public financing program, has been tough for many voters to narrow down as they also make choices for City Council, other offices and ballot questions. There’s also been a dearth of public polling to confirm which candidates might be catching traction in the weeks since a pair of February polls reported that no candidate had registered support above the single digits.

It’s possible some voters will throw up their hands and wait for the runoff on June 6. For now, several prominent elected officials and major unions have stayed on the endorsement sidelines.

But the race isn’t all a muddle. Seven candidates have the best shot of making the runoff, according to a range of outside political observers and campaign insiders who shared their reads of the race based on both clear ground signals and more subtle factors. So long as nobody receives more than 50% of the vote — the requirement to win outright on Tuesday — the top two finishers will advance to the next round.

RELATED: Denver voter guide: Stories, explainers and endorsements for the 2023 election

Mejía suspects they potentially could make the runoff with as little as 15% of the vote.

“It’s anybody’s race — it’s going to be whoever gets out the vote” among those top contenders, said Jeff Fard, a Five Points community activist, also known as Brother Jeff, who’s closely followed the election.

Here’s a look at which candidates are best positioned and the factors, besides strong fundraising, that could propel them to the runoff.

Kelly Brough

The moderate candidate has attracted a raft of establishment endorsements, including from former Gov. Bill Ritter, past Denver City Council members and current suburban mayors. Wide backing from the business community has helped make her the top fundraiser. A former chief of staff to then-Mayor John Hickenlooper before she led the Denver Metro Chamber of Commerce, Brough lacked a recognizable name among most voters. But she’s met that challenge with a constant stream of TV ads introducing herself, along with her compelling personal story.

An outside group has spent nearly $1 million backing her up with a separate ad campaign and ground game. Brough earned the endorsement of the Denver Gazette’s editorial board, along with the backing of former candidate Kwame Spearman.

Mike Johnston

After running unsuccessfully for governor and U.S. senator, Johnston has mounted a strong campaign for mayor, defined by a positive outlook. The former educator and state senator from northeast Denver has relied on strong ties within his former district — including in the Black community, despite a campaign flyer misstep — while tapping a wide donor network that was buttressed by his time leading Gary Community Ventures, a philanthropic foundation.

His allies are on track to spend more than $2 million independently on mailers and the race’s most robust ad campaign by far, dwarfing the Johnston campaign’s own ads buys. Johnston also earned the endorsement of The Denver Post’s editorial board (which is separate from The Post’s news operation).

Leslie Herod

The state representative entered the race with a strong base of supporters, owing to years of prominent work in the legislature on criminal justice reform and other issues. TV ads haven’t figured strongly in her campaign strategy, which was focused on building a network of neighborhood-level grassroots supporters early on. She attracted the early endorsement of former Mayor Wellington Webb, along with backing from notable figures in local and state politics, including former Colorado first lady Dottie Lamm.

Herod has benefited from an outside group that’s spent nearly $170,000 in support of her candidacy, including on modest TV ad buys and canvassing.

Lisa Calderón

Though she hasn’t held elected office, Calderón has built on her support base from the 2019 mayoral election, when she won 18.5% of the vote to finish third. She also has strong community ties from activist work on criminal justice and Latino issues. Recently Calderón, the leader of Emerge Colorado, won the backing of a trio of progressive groups, including the Colorado Working Families Party and the Denver Democratic Socialists of America, that also are working to elect progressive City Council candidates — though that coordination has prompted recent campaign finance complaints.

That backing, along with confident debate performances, should help Calderón compete with Herod for progressive voters. Though Calderón hasn’t bought any TV ad time, she gained one strength, through luck, that no other candidate has: the top ballot position.

Chris Hansen

It would be easy to count out the state senator from east Denver. He took a risk by being the first candidate to air campaign ads, starting in mid-February, but was unable to sustain the initial pace of ad buys after fundraising failed to keep up. But Hansen has a base of support and name recognition from six years in the legislature, along with endorsements from several current and former legislators and former Gov. Roy Romer. He’s also drawn modest outside spending support in recent weeks.

Deborah “Debbie” Ortega

The three-term at-large City Council member is the only candidate that voters have seen on their ballots in each of the last three municipal elections — and she led the field of at-large candidates citywide each time. Ortega, who earlier represented a council district in west and northwest Denver for several terms, has deep ties in the Latino community. She’s drawn a raft of endorsements from political figures from the city’s past, including state Sen. Lucía Guzmán, and has been endorsed by several unions, including those representing Denver sheriff’s deputies and firefighters; the latter union has reported spending more than $120,000 independently in support of Ortega.

Andy Rougeot

The entrepreneur and Army veteran could be the biggest stretch on this list, since he’s a Republican running in a city with just shy of 10% of voters sharing his affiliation. But the largely self-funding candidate — he’s reported loaning his campaign $850,000 so far — has hammered messages focused on getting tough on crime and cracking down on homelessness in a year many are frustrated with those problems. His ad, connecting his military service in Afghanistan to his mission for Denver, has been a fixture on TV for weeks.

Stranger things than a Republican breaking through could happen, but as political analyst Eric Sondermann points out, it’s likely that a moderate such as Brough will siphon off conservative voters who see her as more viable in a runoff.

The rest of the field

Several other candidates have broken $100,000 in fundraising, demonstrating healthy bases of support, even if they were aided by public matching funds. Ean Thomas Tafoya and Terrance Roberts, in particular, entered the race with experience in grassroots activism.

Don’t write off the chance that a lesser-known candidate might break through to finish among the top names, especially with six of the seven leading candidates — all but Calderón — clustered in the second half of the ballot order.

Stay up-to-date with Colorado Politics by signing up for our weekly newsletter, The Spot.