Dan Janison Melville. N.Y. Tuesday January 26, 2010. Daniel Janison,

Dan Janison has been a reporter at Newsday since 1997.

It always seems hard to imagine, while watching primary rivals attack each other, how the losers -- and more importantly their supporters -- could unify behind the winner once the battle ends.

This season, it becomes increasingly tough to believe that those jostling for New York City's Democratic mayoral nomination will achieve anything resembling a kumbaya moment following their Sept. 10 contest and expected Oct. 1 runoff.

Two Republican nominees have won the past five general elections for mayor largely by getting Democratic voters to shed all party loyalty -- that is, by gaining support, or at least indifference, from voters who had preferred the loser of their own party's primary.

A petulant Anthony Weiner brought that dynamic to mind Monday in an interview with the BuzzFeed website. He said the fact that City Council Speaker Christine Quinn helped alter term limits disqualified him from backing her.

What Weiner did not say was that if she had not done so, perhaps he would have stayed in the 2009 race and won. Instead, Weiner folded that year when it became legal for Mayor Michael Bloomberg, with his overwhelming personal campaign resources, to seek re-election to a third term.

As for other rivals, Weiner used language that might as well have come from a GOP candidate.

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"[Bill] de Blasio, Quinn, [Bill] Thompson -- these guys all come from the same place. They're all chasing the same union support. They're all not taking positions on the same issues because they're intimidated by that base of support," Weiner charged.

Long before Weiner declared for mayor, Public Advocate de Blasio, ex-comptroller Thompson, Comptroller John Liu and others worked to knock Quinn off her "front-runner" perch by citing the third-term vote, a federal probe on her watch over legislative spending items and other issues.

Quinn, Thompson and others have all taken shots at de Blasio, who Tuesday for the first time was found leading the pack with 30 percent in a Quinnipiac poll. And Quinn has answered de Blasio's blasts by accusing him, for example, of flip-flopping on term limits himself -- and it is as difficult now to picture her endorsing de Blasio in October as vice versa.

Not that Republican candidates are in warm-and-fuzzy mode. John Catsimatidis keeps tweaking rival Joseph Lhota over the latter's role in raising tolls and fares while he chaired the Metropolitan Transportation Authority. And rival candidate George McDonald accused Catsimatidis of thuggery for once saying he expected the Doe Fund founder to "disappear" as a candidate.

In 2001, when Mark Green beat Fernando Ferrer in a Democratic runoff, much attention turned to the Ferrer camp's refusal to support Green against Bloomberg in the general election. The split had a racial tinge -- though some saw it as contrived -- that so far is absent this year. It centered on Green supporters in a mostly white Brooklyn neighborhood distributing fliers adorned with a New York Post cartoon that portrayed Ferrer in a submissive pose behind the Rev. Al Sharpton.

In 2005, runner-up Weiner made a show of conceding to Ferrer, who narrowly avoided a runoff. But Bloomberg was a strong favorite for re-election, and was supposed to leave in another four years, so Democratic "unity" had little impact.