The Democratic Party suddenly faces the prospect of having to play defense in pockets around the state this fall, as Congressional districts once considered safe for the party have become more vulnerable, partly as a result of new Congressional maps put in place by a federal court. For months, national Democrats had been counting on gains in New York to help the party pick up a few of the 25 additional seats it needs to reclaim the House. The situation developing in New York could undermine that strategy. But top Democrats insist that their incumbents are in strong positions and that the party will pick up seats, particularly since President Obama is at the top of the ticket and remains popular throughout the state. House Republicans face their own challenges in the state, as top Democrats in Washington point out. Several Republican incumbents — most of them freshmen who took office in 2010 with the Tea Party support — must defend their seats against potentially strong Democratic challengers. The Democrats Representative Kathy Hochul, District 27 A first-term Democrat, Ms. Hochul is considered among the most vulnerable Democratic incumbents in New York. She achieved national prominence last year when she won a special election in a conservative district in the Buffalo area by turning the race into a referendum on a Republican proposal in Washington to overhaul Medicare. The new Congressional map has made her district even more Republican, making her re-election prospects more difficult. Two Republicans are seeking the nomination to run against her: Chris Collins, the former Erie County executive; and David Bellavia, a veteran of the Iraq war and a Tea Party activist. Representative Louise Slaughter, District 25 After serving nearly 25 years in Congress, Ms. Slaughter may be facing the most difficult challenge of her career. As a result of the new Congressional map, her district was consolidated into Monroe County, becoming slightly more Republican but still predominantly Democratic. Now, Maggie A. Brooks, the popular Republican county executive in Monroe, has entered the race to unseat Ms. Slaughter, buoyed by the fact that her political base is in the heart of the congresswoman’s new district. Representative Bill Owens, District 21 Mr. Owens, who represents this conservative district in northernmost upstate New York, initially won his seat in a 2009 special election and was re-elected the next year. In both instances, Mr. Owens won with less than 50 percent of the vote. And in both instances, his candidacy was helped by a third-party Conservative candidate who undercut the Republicans. But that is unlikely to happen this year because Republicans and Conservatives appear to be coalescing behind Matthew A. Doheny, the Republican candidate who lost to Mr. Owens in 2010. Another Republican, Kellie Greene, is also seeking to run against Mr. Owens. Representative Timothy H. Bishop, District 1 On Long Island, Mr. Bishop, a five-term Democrat, is girding for a rematch with Randy Altschuler, a successful Republican businessman who nearly defeated the congressman in 2010. Mr. Altschuler is an aggressive campaigner, having spent $2.9 million of his own money in 2010. Mr. Altschuler got a lift recently when he received the endorsement of the Independence Party. That could make a difference, Republicans say, given that Mr. Altschuler lost to Mr. Bishop by a slim margin in the moderate district, which stretches across the eastern half of Long Island. The Republicans Representative Ann Marie Buerkle, District 24 Ms. Buerkle, a Republican, who won her seat in the Syracuse area in a big upset in 2010, is hoping to prove that her election was no fluke. But Republicans and Democrats alike say Ms. Buerkle, a Tea Party favorite, faces an uphill battle in the new district, which analysts say leans Democratic. Ms. Buerkle is going up against the man she defeated in 2010, Dan Maffei, an aggressive campaigner who has already amassed about as much money as she has. Representative Chris Gibson, District 19 The new Congressional map severely undercut Mr. Gibson, a first-term Republican who won in 2010. Mr. Gibson’s district went from being a Republican-leaning district to a swing district that Democrats believe they have a strong shot at picking up. Mr. Gibson is facing a challenge by a political newcomer, Julian Schriebman, a former chairman of the Ulster County Democratic Party who is running on his experience as a federal prosecutor who tried terrorists. Representative Nan Hayworth, District 18 In 2010, Ms. Hayworth, a first-term Republican from the suburbs north of New York City, won her seat with strong Tea Party support against a Democratic incumbent who fellow Democrats say underestimated her. But Democrats and independent analysts say she is vulnerable this year. No fewer than four Democrats have lined up to run against her, including Sean Patrick Maloney, an aide to former Gov. Eliot Spitzer; Tom Wilson, the mayor of Tuxedo Park; Rich Becker, a town councilman in Cortlandt; and Matt Alexander, the mayor of Wappingers Falls. Representative Michael G. Grimm, District 11 Mr. Grimm, a Republican who captured his seat in 2010 with strong support from the Tea Party, has found himself enmeshed in a controversy that Democrats say makes him vulnerable. Mr. Grimm, who represents a district that includes Staten Island and part of western Brooklyn, has been facing intense scrutiny after The New York Times reported in January that his lead fund-raiser in the 2010 campaign was under investigation by the Federal Bureau of Investigation. Some donors said Mr. Grimm and the fund-raiser indicated that they would accept illegal donations. Republicans have stood behind Mr. Grimm, who has denied any wrongdoing. Democrats, in the meantime, are getting behind Mark Murphy, the son of a former congressman, after failing to recruit Michael E. McMahon, the candidate who lost to Mr. Grimm in 2010.
