WASHINGTON —  Sen. Hillary Clinton is defending her contribution to a Democratic Senate candidate who opposes abortion, saying he is needed for the party's struggle against Republicans.

Clinton, an abortion rights supporter who many people think will run for president in 2008, acknowledged Monday she had contributed $10,000 last year from HillPAC, her political action committee, to Pennsylvania State Treasurer Bob Casey, a Democrat challenging Republican Sen. Rick Santorum.

Casey is running well ahead of Santorum in many polls but is meeting fierce resistance from some women's organizations because of his anti-abortion stance.

Clinton called Casey a "real champion" on issues like health care for needy Americans.

"Regardless of what differences there may be among Democrats, the differences between Democrats and Republicans today could not be starker," Clinton said at a news conference. "And if we can move toward a Democratic majority, we can prevent some of the ill-advised legislation and nominations we have to deal with from ever seeing the light of day."