The Kings County Republican Party is expected to endorse Mayor Bloomberg next week, The New York Sun was told yesterday. The Brooklyn support is meant to provide momentum to Mr. Bloomberg’s re-election bid and would level yet another blow at the upstart campaign of Mr. Bloomberg’s Republican challenger Thomas Ognibene.

The Kings County party’s executive committee will not actually cast their votes to choose who will win the endorsement until next week, officials close to the discussions told the Sun. But officials said they expect Mr. Bloomberg will emerge with their backing. Mr. Ognibene secured the Queens County party endorsement earlier this year, but the mayor later won the Bronx organization’s endorsement and is expected to secure the backing of the Richmond and New York county party organizations as well.

“What this means is that Ognibene is quickly becoming a one-county candidate,” a political consultant, Hank Sheinkopf, said. “Republicans have finally come to the conclusion that they don’t want to be part of a coup against the mayor.”

Landing the Kings County endorsement so early in the campaign is also indicative of something else: Mr. Bloomberg’s newfound political acumen. While the mayor continues to repeat that he isn’t a politician, his actions say otherwise. He has learned a lot about politics in the past three years, analysts said.

“His political skills have made a huge leap forward,” a deputy mayor from the Dinkins administration, Barbara Fife, said. “Look at the Cross Harbor train. That was a very political decision – but it doesn’t make it a wrong decision. He made the call out of sensitivity to a community that feels neglected.”

Last week Mr. Bloomberg showed up at a community forum at Middle Village, Queens, and announced that he would oppose a controversial freight rail tunnel project to link Brooklyn and New Jersey. While his own Economic Development Corp. was supporting the project as a better way to transport goods to the city and an environmental boon, the mayor decided to side with the neighborhood instead.

“I think in this case you really would destroy neighborhoods here in this area and you just can’t do that,” Mr. Bloomberg told an audience at Our Lady of Hope Church at Queens, as residents roared their approval. “I think when you get done looking at all of the pros and cons, the answer is that we should not build this tunnel.”

That stand put Mr. Bloomberg in direct opposition to three of the four Democrats vying for his job. The speaker of the City Council, Gifford Miller, of Manhattan; Rep. Anthony Weiner, who represents a Brooklyn-Queens district, and the borough president of Manhattan, C. Virginia Fields, all have supported the multibillion-dollar project.

It also robbed Mr. Ognibene of an issue. He had been a loud critic of the project, and with Mr. Bloomberg stepping into that space it gives the former council minority leader one less issue with which to distinguish himself from the mayor, analysts said. “It was smart politics,” Mr. Sheinkopf said.

Ms. Fife, too, praised the reluctant politician.

“Bloomberg likes to interject that he is ‘not political,’ but I don’t think ‘political’ is necessarily a pejorative term,” Ms. Fife said. “I don’t know why he is skittish about that word. That’s the game he’s in now, and he’s playing it very well.”

The Kings County endorsement is part of that. Brooklyn GOP leaders said that in the wake of Mr. Ognibene’s Queens coup they had been expecting him to lobby for their support as well, but he never came calling. Mr. Bloomberg’s political operatives did.

In a typical year, the county organizations make their endorsement announcements in April with an eye to a May 15 deadline they must meet to print petitions. Mr. Ognibene’s decision to brandish an early Queens endorsement sped up the timetable, party officials said.

While the Republican organizations outside Queens are said to have closed ranks around Mr. Bloomberg, there had been some grumbling behind the scenes, political analysts said. Among the complaints is the feeling that Mr. Bloomberg’s campaign operatives are convinced that everyone has a price. Whether the perception is what the mayor’s team, with its deep pockets, really projects, or just what party members sense, is unclear.

They had also complained about Mr. Bloomberg’s absence from GOP club meetings and his disdain for the grassroots schmoozing that usually occurs between candidates and the local party faithful. Increasingly, that, too, has been changing as Mr. Bloomberg has kicked his campaign into a higher gear. His schedule, now replete with outer-borough events and community meetings, shows the shift in emphasis.

“What you are seeing is a Mike Bloomberg who is now managing the politics of the city instead of just running the city,” Mr. Sheinkopf said. “He is making more personal calls, and he is out and about more, and that is making a difference for him.”

Even if Mr. Bloomberg weren’t on the stump, his predecessor Ed Koch said, he would probably get re-elected on the merits.

“I would like a full-page ad in the Sun with me saying ‘Why I am for Michael Bloomberg,” Mr. Koch said yesterday. “I tried to get control of the Board of Education and failed, and he got it. Race relations have never been as good as they are in town today. There is nothing wrong with being politically motivated if it is also on the merits, and with him the decisions are on the merits.”