WASHINGTON – Maine Sen. Susan Collins said Friday that she will vote to confirm Elena Kagan as a Supreme Court justice, breaking with her party to back President Obama’s nominee.

Collins’ announcement made her the third Republican senator to support Obama’s choice to succeed retired Justice John Paul Stevens. It doesn’t alter the positive outlook for Kagan in the Senate, where she was already well on track to be confirmed in early August by majority Democrats and a handful of Republican moderates.

Collins said in a statement that Kagan has “the intellect, experience, temperament and integrity” to serve honorably on the high court.

“To be clear, in her previous posts, Ms. Kagan has taken positions that I oppose,” including on gun rights, Collins said of the Obama administration’s solicitor general, who previously served as a Clinton administration aide and as dean of Harvard Law School.

But Collins said that she believes Kagan deserves to be confirmed based on her record, her character and her promises to adhere to precedents, including in cases in which the Supreme Court recognized gun ownership as an individual right protected by the Constitution.

Collins divulged her plans at the end of a week in which two other Republicans announced they will back Kagan. Sen. Lindsey Graham of South Carolina was the first to do so as the Senate Judiciary Committee approved Kagan’s nomination, and Richard Lugar of Indiana followed suit the next day.

Most Republicans, however, plan to vote against Kagan, arguing that she would put her politics ahead of the law and be a rubber stamp for Obama’s agenda. She’s also drawn fire from anti-abortion and pro-gun rights groups, which contend that she’s hostile to their causes.

Sen. Lamar Alexander, R-Tenn., said Friday he will oppose Kagan based on her decision to bar military recruiters from Harvard Law School’s campus career services offices because of the policy against openly gay soldiers.

The Pentagon said Kagan’s move — which she has said was designed to comply with Harvard’s nondiscrimination policy — made the school ineligible for federal funding under a law requiring equal campus access for military recruiters.

The episode “leads me to believe that she would use her authority as a Supreme Court justice to advance her own policy preferences,” Alexander said in a statement.

Sen. John Ensign, R-Nev., also pointed to the recruitment flap in announcing he will vote against Kagan, saying she “dishonored the military.” He said Kagan had shown a hostility toward gun rights and a “propensity toward political activism” that led him to conclude she’d be a liberal activist on the Supreme Court.