Chris Romer, James Mejia and Michael Hancock are effectively tied for the lead, according to the poll, with a margin of error around 4 percentage points.
Romer and Mejia are tied with 22 percent of the support from those polled in an automated telephone survey, while Michael Hancock has 18 percent.
The survey took into account the opinions of 588 likely voters in the race.
"What we're looking at right now is pretty much a three way race," RBI Strategies Partner Craig Hughes said. "You've got Chris Romer, James Mejia and Michael Hancock really competing for first place."
The Denver Post/9NEWS poll shows different results from the RBI Strategies/Coloradopols.com poll, released two weeks ago.
That poll showed Chris Romer with 22 percent of voter support, James Mejia with 10 percent and Michael Hancock with 9 percent.
"Polls are a snapshot in time," Hughes said. "I still put Chris Romer in the driver's seat. The vote that he has in this poll and what we showed in our poll is that he is in better position among the likely voters."
The Denver Post/9NEWS poll placed other candidates at quite a distance from the top three.
Doug Linkhart garnered 10 percent support, while Carol Boigon showed a surprisingly low 8 percent of the vote. According to political analysts, Boigon's low poll number is surprising because she has spent much of her own money on advertising.
"The fact that Carol Boigon has spent as much money as she has on advertising," Katy Atkinson, a political consultant with Atkinson and Associates, said, "It hasn't done much for her."
Boigon's numbers have not really moved from the RBI strategies poll, where she garnered 5 percent of the support, Hughes said.
"The troubling thing to me for Carol Boigon is she lacks a real base," he said.
Theresa Spahn trails the top five with 4 percent support, while another 6 percent say they'll vote for one of the other four candidates on the Denver mayoral ballot. Another 11 percent are undecided.
The Denver Elections Division started mailing ballots to voters this weekend.
Candidates will have to energize their bases to mail their ballots back, analysts say, to have an advantage over each other in the short amount of time until they are due May 3.
"The top three have developed a strong base of support," Hughes said. "Chris Romer is doing very well with older voters, James Mejia with Hispanic voters, Michael Hancock with African American voters."
Romer has support from 23 percent of voters more than 50 years old.
Analysts say those voters are more likely to vote in an off-year municipal election.
Mejia has support from 45 percent of Hispanic voters, while Hancock has 43 percent from African-American voters.
Eleven percent of likely voters are undecided according to the Denver Post/9NEWS Poll.
"I think we probably have a larger undecided factor than this poll is showing," Atkinson said.
She also says undecided voters may not mail their ballots back.
As for issues in the race, voters want candidates to focus mostly on jobs, economic development, schools and the city's budget.
"What the internals are showing is a very interesting race developing," Hughes said.
The race will most likely move to a runoff, scheduled for June 7. In order to avoid the runoff, one candidate would need to get at least 50 percent of the May 3 vote, and no candidate is close to that level of support.
"I think the question is: How close is the first and second spot going to be?" Atkinson said.
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