When Gifford Miller announced endorsements from a group of Brooklyn elected officials last month, he did so in the political backyard of his Democratic mayoral opponent Rep. Anthony Weiner.

When Mr. Weiner talks about relocating the controversial stadium that Mayor Bloomberg is pushing for Manhattan’s West Side to Queens, he has been known to throw in a jab at Mr. Miller for embracing the idea only belatedly.

But Mr. Miller, who is the speaker of the City Council, and Mr. Weiner, whose House district includes portions of Brooklyn and Queens, actually have quite a bit in common.

They overlapped as members of the council. They are in the same age bracket. And they both are white. Political analysts say those similarities are precisely why it will be difficult for both of them to advance from September’s Democratic primary to a potential run-off involving two of the four candidates.

Recent polls from Quinnipiac College have the two tied at 12% in the Democratic race, while the front-runner, Fernando Ferrer, is at 40%, and the only woman and only African-American in the race, C. Virginia Fields, is at 14%. The remaining 22% in the sample of enrolled Democratic voters said they were undecided.

How either the Weiner or the Miller camp can break out of the last-place tie is an as-yet-unsolved puzzle. Both candidates are keeping long hours, making appearances at community meetings from Staten Island to the Bronx in an effort to cobble together a coalition that will get them into at least a primary runoff.

Estimates from Prime New York, a political consulting firm, suggest that roughly 40% of registered Democrats in the five boroughs are non-Hispanic white, 31% are black, 25% are Hispanic, and 3% are Asian.

Based on historical voting patterns that show different ethnic groups tend to vote for candidates who resemble their own demographics, political analysts said Messrs. Weiner and Miller have a problem. Even if whites are a plurality of primary voters, a candidate who wins half of the white Democrats’ votes, and no others, has no chance.

“Gifford has to break into Weiner’s world, which is outer-borough whites, and Weiner has to break into Gifford’s world, which is Manhattan,” a political consultant, Hank Sheinkopf, said during a phone interview yesterday. “They’re going to have to fight each other to the death, because only one of them can survive into the runoff.”

There are no signs, however, that either candidate is planning to bow out of the race. Mr. Miller is being forced out of his Upper East Side council seat by term limits and has already raised $5.7 million for his mayoral run – more than any of the other three Democrats. Mr. Weiner, who aides said will report to the Campaign Finance Board today that his fund-raising total has hit $1.9 million, does not have to give up his congressional seat. Neither man has anything to lose by staying the course – and either man stands to gain increased name recognition for a future campaign.

Any contentious remarks, some consultants said, serve to garner more exposure for both of them. Late last month, when Mr. Weiner criticized the council for approving zoning changes on the West Side in the area around the proposed stadium, one newspaper quoted Mr. Miller’s spokesman dismissing the attack as “tired, political potshots.” Mr. Weiner, meanwhile, has referred to both Mr. Miller and Mayor Bloomberg as “out-of-touch Upper East Side rich guys.”

“To some extent, battling is going to help them because it’s going to raise their profiles,” a Republican political consultant, Michael McKeon, said.

Mr. McKeon said, though, the battle was a “double-edged sword” and the two candidates would undoubtedly hold each other back. “I think they’re going to battle each other right over a cliff,” he said.

Last week, a staff member in Mr. Miller’s council office, Marie Ternes, defected to join Mr. Weiner’s campaign. A spokesman for Mr. Miller, Stephen Sigmund, said she was a junior person in the council’s policy division, who played a small role and had worked in the office for only about eight months.

Yet one council staff member who declined to go on the record said the speaker’s office was “incensed.” The incident highlights that there is a limited supply of campaign talent to be hired and that even when a junior person leaves, there is a feeling of betrayal when that person goes to the other guy.

A spokesman for Mr. Weiner, Anson Kaye, said yesterday there was “no bad blood” between the two.

“We are focused on the ideas that are really the engine of this campaign,” Mr. Kaye said.

And what about other political candidates? “That’s not really part of the calculus,” he said. “Our objective is to tell as many people as we can about the congressman’s ideas for how to make New York City a place where working families can prosper.”

A spokesman for Mr. Miller’s campaign, Reggie Johnson, also directed his comments away from political strategy, saying the speaker would “continue to make his case directly to New Yorkers.”

“That is the speaker’s focus regardless of who enters the race,” Mr. Johnson said yesterday.

Last week, it was reported that Mr. Ferrer, the former Bronx borough president, and Ms. Fields, the Manhattan borough president, had agreed not to attack each other as they campaign. The goal is to avoid a repeat of the 2001 election, when negative campaigning in the Democratic primary is believed to have worked in favor of the Republican, Mr. Bloomberg, in the general election.

Ms. Fields’s campaign adviser Joseph Mercurio exuded confidence about his candidate yesterday and said he thought it would be hard for Messrs. Miller and Weiner to collect enough votes in September. But he said all the Democratic candidates needed to get behind whoever wins the nomination.