Michael Hancock, James Mejia and Chris Romer are all in a dead heat according to a Denver Post/9NEWS poll released last week.
The other six candidates on the ballot have 10 percent or less of the support in the Survey USA poll.
Wednesday, the leading three campaigns spent the morning and afternoon trying to reach undecided voters.
"We're still persuading them that I'm the right person to put this city back to work," former State Sen. Chris Romer said while at his campaign headquarters near City Park.
Romer made phone calls to voters, trying to drive home a message: he has the experience to run city government at the speed of business.
"The other two candidates [Hancock and Mejia] have spent their whole lives in government," Romer said. "I've spent my life in both the government and the private sector."
Denver City Councilman Michael Hancock chose not to engage with Romer or Mejia Wednesday at a campaign stop at Bruegger's Bagels in downtown Denver.
"Me bickering with James or Chris is not going to get people working," Hancock said. "It's not going to put food on people's table. It's not going to get the public safety department to restore its trust with the public again."
Hancock says he was bolstered Wednesday by the endorsement of Denver business leader Walter Isenberg. Isenberg was widely rumored to have considered a run for mayor earlier this year, but chose Wednesday to endorse Hancock.
"Walter is a well-respected business leader and generous member of our community and I am honored to receive his staunch support," Hancock said.
Mejia spent Wednesday afternoon asking for support from business leaders in Denver's Five Points neighborhood.
Mejia, the CEO of the Denver Preschool Program and manager for the Denver Justice Center project, says he has more executive leadership experience than Hancock and Romer.
"When you hear from each and every candidate as to what they've personally been accountable and responsible for, the difference is a magnitude," Mejia said. "Having spent my time [as an] executive is a big difference in regards to the other candidates."
As of Wednesday, just more than 38,000 voters had turned in their ballots to the Denver Elections Division. There are still nearly 242,000 ballots unreturned.
"This could be a race decided by a few thousand votes on May 3, because partially it looks like very few people are voting," 9NEWS Political Analyst Floyd Ciruli said.
Ciruli says it will most likely be Mejia, Hancock and Romer competing for the two runoff spots, as opposed to Doug Linkhart and Theresa Spahn, who both had ten percent or less of the support in the recent Denver Post/9NEWS poll.
"There's very very little left for one other candidate to suddenly go to 20 or 25 percent," Ciruli said. "The math just doesn't work."
"For either [Doug] Linkhart or [Theresa] Spahn at this point would be very, very difficult largely because they lack media money, they've got much smaller get out the vote operations," Ciruli said.
Linkhart responded Wednesday saying with low voter turnout, name recognition will benefit him. He also highlighted his name is first on the ballot.
"I've been elected seven times. People know me. Those people I'm counting on again," Linkhart said. "I don't think one poll makes an election."
Spahn says she is receiving lots of support, as well, receiving recognition in the community from the 41 forums she has attended.
"We have a huge volunteer base," Spahn said. "We have already touched over 12,000 doors."
"Even through today [Wednesday], we're still finding a lot of undecided voters," she said.
All ballots have to be received at the Denver Elections Division by May 3 at 7 p.m.
If no candidate gets more than 50 percent of the vote, which is a likely outcome, a runoff election will be June 7.
(KUSA-TV © 2011 Multimedia Holdings Corporation)