Prompting the exchange was a 5-4 decision by the Supreme Court that struck down a Nebraska law barring a late-term procedure that opponents call "partial-birth" abortion.
Vice President Al Gore said the "razor-thin" margin of the high court's decision should sound an alarm to abortion-rights supporters not to elect Bush as president.
"One extra vote on the wrong side ... would change the outcome and a woman's right to choose would be taken away," Gore said during a campaign stop outside Columbus, Ohio.
Gore reminded listeners that Bush has identified Justices Antonin Scalia and Clarence Thomas -- both abortion-rights opponents -- as models for any judicial appointments he would make if elected.
Bush has shied away from saying he would nominate only anti-abortion judges, saying instead that he would nominate "strict constructionists" in their interpretation of the Constitution. He also has said he believed the Supreme Court overstepped its bounds in the Roe vs. Wade ruling.
Gore called his Republican opponent an extremist posing as a moderate on the abortion issue.
"His state under, his governorship, has become the place where a woman's right to choose is least available, least protected and least defended. He has promised to do his best, with (judicial) nominations, to overturn Roe v. Wade," Gore said.
"This is now clearly an important issue in this presidential campaign," Gore added.
Bush campaign spokeswoman Karen Hughes said, "Governor Bush is disappointed by the Supreme Court decision. Unlike Al Gore, Governor Bush is opposed to the particularly gruesome procedure known as partial-birth abortion."
"The majority of the American people agree with Governor Bush. He believes that it is possible to enact a ban on partial-birth abortion in a constitutional way, and unlike Vice President Gore, when he is elected president, Governor Bush will work to do so," Hughes said.
In the past, Bush has said he supports the Republican platform's ban on abortion in all cases. But he's also said he favors exceptions to the ban in cases of rape or incest or to protect a woman's life.
The inflamed abortion debate comes as Bush endeavors to keep the issue from consuming the Republican National Convention. Some anti-abortion conservatives have been wary of Bush's resolve on abortion, especially as he courts moderate support.
On Thursday, a coalition of anti-abortion leaders including conservative activist Phyllis Schlafly and current and former presidential candidates Alan Keyes and Gary Bauer met in Washington to urge Bush and the GOP to re-adopt the strong anti-abortion language of its 196 party platform.