Among the most troubling losses for New York Republicans in last week’s elections may have been in rural Rensselaer County, the home district of the state Senate’s Republican majority leader, Joseph Bruno. In a possible sign of Mr. Bruno’s own vulnerability, his picks for county judge and Rensselaer mayor both lost to Democrats.

One top Republican, who asked not to be identified, said that Mr. Bruno refuses to accept blame for last week’s defeats. He said Mr. Bruno told colleagues at a dinner last week that the losses could be chalked up to President Bush’s low popularity numbers.

A vice chairman of the state Republican State Committee, Vincent Reda, agreed.

“I think obviously the president’s poll numbers being down as low as they are certainly had an effect,” Mr. Reda said. “But I’m optimistic enough to think we’ve got 12 months to make it up. I think the president will, and I know certainly in New York we’re in good shape.”

Other Republicans offered a gloomier outlook. They said that with a popular incumbent, Senator Clinton, leading the Democratic ticket next year, Republicans will be at an even greater disadvantage. A former executive director of the Republican State Committee, Brendan Quinn, predicted that in November 2006, Republicans will lose their 39-year hold on the state Senate.

“You’re not going to win with the same old leadership if people aren’t happy with the current leadership,” Mr. Quinn said. “You have to shake things up.”

Loyalty has traditionally been strong among state senators. Mr. Bruno staged a takeover of the upper chamber with Mr. Pataki’s blessing in 1994, but such challenges are rare. In recent days, however, speculation has increased that several Republicans could stage primaries against sitting Republican senators next year to shake up the establishment.

One member of the Senate Republican leadership, Senator Golden, of Brooklyn, blamed the losses on the candidates. He declined to lay blame on Messrs. Bruno or Pataki, or the chairman of the Republican State Committee, Stephen Minarik.

“I think the Republicans definitely have to get their act together,” Mr. Golden said. “I think, in certain cases, we didn’t have our act together. Some are going to blame Bush for this set of losses. I think you can only blame Bush for so much. If you’re on top of your game, your constituents are going to vote for you. If you’re not, they won’t.”

Mr. Bruno, 76, told the Associated Press last week that he is confident none of his Senate colleagues will vote against his re-election as majority leader next year. But there are fresh signs that a challenge to Mr. Bruno’s leadership could come from without.

The Democratic chairwoman of Rensselaer County, Lynne Mahoney, said yesterday that she is interviewing potential Democratic challengers for Mr. Bruno’s seat. The last time a Democrat ran against Mr. Bruno, who was first elected in 1976, was 1996.

“We’ve had some people express interest, and there’s a very good chance we’ll be putting up a candidate for that office,” Ms. Mahoney said. “It’s not only the crack in the foundation of the Republican Party we’re now seeing, but you’re starting to see water gush through.”