CONCORD, N.H. (AP) -- An abortion rights group wants all the Republican presidential candidates in Thursday's debate to come clean about whether they intend to ban abortion, but it reserves special criticism for George W. Bush.

The National Abortion and Reproductive Rights Action League continued its series of ads against Bush on Wednesday, claiming he will appoint anti-abortion judges to the Supreme Court if elected president.

The 30-second spot running on WMUR-TV intersperses images of the Supreme Court building with photos of Bush. It claims Bush would appoint judges who would overturn the Supreme Court's 1973 Roe vs. Wade decision that legalized abortion.

''The next president of the United States may have the opportunity to end legal abortion,'' a female announcer says. ''And that is just what George W. Bush wants to do.''

Bush has said he would not nominate Supreme Court justices based on their abortion views. He has also said he would support a constitutional amendment limiting abortion rights, but would not push for it.

''He will appoint people to the Supreme Court who share his conservative philosophy strict constructionists who will interpret law, not make law from the bench,'' Bush spokesman Scott McClellan said Wednesday.

''Americans are tired of these kind of third party special interest group attack ads,'' he said. ''They are ready for the new style of positive campaign Gov. Bush is running and always has.''

In a telephone interview, NARAL President Kate Michelman said all the candidates should ''declare unequivocally whether they will use the power of the presidency to end legal abortion.'' However, the ad focuses exclusively on Bush, the governor of Texas.

The release of the ad was timed to coincide with the Republican candidate forum scheduled for Thursday night on WMUR. It will be the first time Bush has appeared with the other candidates.

Michelman said all the Republican candidates are equally anti-abortion, but ''George W. Bush, frankly, is the frontrunner.''

''He is the candidate who has the obvious momentum to win the nomination. We've got to choose our target,'' she said.

However, if Arizona Sen. John McCain ''moves out of New Hampshire strongly and really does look like he's going to mount a serious challenge to George W. Bush, we will do what we have to do,'' she said.

The Supreme Court ad is the group's third that focuses on Bush. In March, ads in New Hampshire and Iowa accused him and Elizabeth Dole of concealing their anti-abortion views while on the campaign trail. Dole has since dropped out of the race. A similar ad in September targeted only Bush.

The latest ad may air in other states later, Michelman said. She would not say how much the group has spent on the ads.