WASHINGTON – With the Senate expected to vote on Supreme Court nominee Samuel Alito as early as Friday, many court watchers are focused on a handful of Democrats from states that went for President Bush last year. Republican political strategists, though, are zeroing in on two Democrats whose states voted against Mr. Bush in the 2004 election.

Republican strategists say they are hoping that strong bipartisan support for Judge Alito in New Jersey and Pennsylvania will divide the Democratic Party in both states and boost a struggling two-term incumbent, Senator Santorum, of Pennsylvania, and an insurgent Republican who leads polls in New Jersey, Thomas Kean. A unique set of circumstances makes Judge Alito popular in both states, and Republicans are using it to their advantage.

The more aggressive push will be in Pennsylvania. Though Judge Alito’s chambers are in Newark, N.J., the federal Court of Appeals where he sits is based in Philadelphia. One of Judge Alito’s most notable rulings was Planned Parenthood v. Casey, in which he was the only judge on a three-judge panel to uphold in its entirety a Pennsylvania law that regulated abortion. The defendant in the case was the father of Mr. Santorum’s opponent, Robert Casey Jr.

“What Casey wants more than anything else is for this thing to go away,” a spokesman for the National Republican Senatorial Committee, Daniel Ronayne, said. “And we’re going to do everything we can to make sure it doesn’t.”

Judge Alito has drawn broad support from Democrats in his home state of New Jersey. A recent television advertisement by the Republican group Progress for America featured a Democratic former attorney general of New Jersey, Robert Del Tufo, endorsing the nominee. And a popular former Democratic governor of the state, Brendan Byrne, has urged New Jersey’s new senator, Robert Menendez, to vote to confirm Judge Alito.

“Alito is not the first choice of liberal Democrats,” Mr. Byrne told the Philadelphia Inquirer last week. “But we recognize that we lost the election. I think Sam Alito is as good as we’re going to get. He’s an excellent lawyer … it’s a tough call for Menendez.”

New Jersey’s new Democratic governor, Governor Corzine, chose Mr. Menendez as his replacement upon leaving the Senate earlier this year. Mr. Menendez has described the vote on Judge Alito as one of the two most difficult choices he will have to make as a senator. Further complicating the choice is the fact that Senator Schumer, a Democrat of New York, has said he helped vet Mr. Menendez for the post.

Mr. Schumer, who is seen as leading the charge among Democrats against Judge Alito, is in a precarious spot himself. The chairman of the Democratic Senatorial Campaign Committee, he is charged with promoting candidates and heading up fundraising for Senate campaigns. Mr. Schumer made a strategic decision last year in choosing Mr. Casey over a pro-choice Democrat, Barbara Hafer, in an effort to overtake the pro-life Mr. Santorum. Mr. Schumer suggested yesterday that Democrats would not attempt to block Judge Alito with a judicial filibuster, a move that would require 40 Democrats to pull off.

“There is no question many are disappointed in some of the answers that Samuel Alito gave,” Mr. Schumer said about Judge Alito’s confirmation hearing on CNN Late Edition. “But to vote against him is one thing, and to filibuster requires what I think is a much higher standard.”

Recent polls show Mr. Casey leading Mr. Santorum by as many as 15 percentage points and Mr. Menendez trailing Mr. Kean by about 10 percentage points. According to a Zogby International poll from the second week of January, the number of undecided votes in New Jersey hovers around 15 percentage points. The president of the polling center, John Zogby, said he does not think Mr. Santorum will get much traction by focusing on Mr. Casey’s silence on Judge Alito’s nomination.

“You can’t blame Santorum for trying on this one,” Mr. Zogby said. “But I think on the life issue, it’s going to be hard to tar any Casey on not being pro-life enough … Santorum can continue to try whatever he can and do whatever he can, but he’s going to have to do a bit more to get his own numbers up first.”

Only one Democrat out of 44 in the Senate so far has said he intends to vote for Judge Alito: Senator Nelson, of Nebraska. Twenty-two Democrats voted for Chief Justice Roberts, and several of those have already said they intend to vote against Judge Alito. Republicans, who number 55, are hoping for more than 60 votes to avoid a filibuster and to give President Bush greater leverage in the event that another seat opens up on the Supreme Court.

Democratic strategists denied that senators and Senate candidates are lining up behind the party’s liberal wing. The spokesman for the Democratic Senatorial Campaign Committee, Phil Singer, called efforts to make the confirmation vote a subject of the New Jersey and Pennsylvania Senate races “disingenuous.”

“A Supreme Court nomination is a serious matter, and it’s unfortunate that some Republicans are intent on politicizing the confirmation process,” Mr. Singer said. “Considering how the Miers nomination was tanked within seconds of conservative groups crying foul, it’s remarkably disingenuous for Republican campaign operatives to suggest that Democrats are beholden to groups on the left. Democrats will decide whether to support or oppose Judge Alito based on their evaluation of him and not anyone else’s.”