President Bush voiced his support by telephone for anti-abortion activists Wednesday as tens of thousands of demonstrators convened in Washington to mark the 30th anniversary of the Supreme Court's Roe v. Wade ruling.

Bush, who has promised to sign any bill that restricts late-term "partial-birth" abortions, told the anti-abortion demonstrators from St. Louis:

"You are gathered today on the National Mall, not far from America's monument to Thomas Jefferson, author of our Declaration of Independence. And the March for Life upholds the self-evident truth of that Declaration -- that all are created equal, and given the unalienable rights of life, liberty, and the pursuit of happiness.

"...And this self-evident truth calls us to value and to protect the lives of innocent children waiting to be born."

Thousands of pro-abortion activists also were marching in the nation's capital, voicing their support for the 1973 ruling that legalized abortion in all 50 states.

But they were far outnumbered by the anti-abortionists, who marched with banners and placards in sub-freezing weather, buoyed by hopes that the new Republican-run Congress will curb the procedure that many of them consider murder.

"It just seems like it's more optimistic this year after the November elections," said Dennis Voglesong, 50, of Hagerstown, Md., who was attending his fifth March for Life. "I see a lot more kids here this year. Every year it seems the youth gets to be a larger part of the movement."

Wednesday's events attracted priests, nuns, political leaders, men, women and children of all ages.

Both sides held competing candlelight vigils in front of the Supreme Court Wednesday night.

Several hundred anti-abortion protesters chanted, "We won't go back," drowning out testimonials at the other vigil from women who have had abortions.

Tens of thousands attended the anti-abortion March for Life -- a lunchtime event dramatized by powerful images, including dozens of crosses and billboard-size color photographs of aborted fetuses.

As onlookers gawked at the pictures, the man who posted them said he felt that images were the best way to spread the message.

"For people to understand the horror of what abortion is, they have to see it," said C. Fletcher Armstrong of the Center for Bioethical Reform. "It's just like people have to go to the Holocaust Museum here to see what the Holocaust was all about."

"Most anniversaries are causes for celebration," said Philadelphia Roman Catholic Archbishop Anthony Bevilacqua, who chairs an anti-abortion committee of the U.S. Conference of Catholic Bishops. "This one is not. It is a day of mourning. Mourning for this immoral, unjust, illogical decision."

Meanwhile, the Planned Parenthood Federation of America held a counter-protest at the Supreme Court. Also Wednesday, the Feminist Majority Foundation began a two-day conference with more than 400 college students discussing ways to maintain abortion rights.

Democratic presidential hopefuls were the guests of pro-abortion groups in Washington the night before.

NARAL Pro-Choice America hosted a dinner attended by 1,300 people, featuring former Vermont Gov. Howard Dean, Rep. Dick Gephardt of Missouri and Sens. John Edwards of North Carolina, John Kerry of Massachusetts and Joseph Lieberman of Connecticut.

In their first joint appearance, the presidential hopefuls pledged to protect abortion rights.

"There is nothing moral in strong-arming a personal belief, and there is nothing moral to a presidency that imposes personal morality through acts of government power," Gephardt said.

Gephardt and Edwards discussed the importance of passing a federal law to guarantee abortion rights even if the Supreme Court should overturn the 1973 Roe decision.

"The right to choose is an essential ingredient to realize the full equality of America," Edwards said.

The Roe v. Wade anniversary comes at a flashpoint in the debate, with anti-abortion activists saying political winds have granted them sympathetic ears among lawmakers in power and afforded them their best chance in years to dent the rights granted by the decision.

Republicans hold the presidency and Congress, and a possible retirement on the Supreme Court could allow Bush to appoint a justice who opposes abortion.

First on the GOP's agenda is passing a ban on late-term abortions. Congress passed a ban on partial-birth procedures in 1996 and 1997, but President Clinton vetoed both bills.

Kim Gandy, president of the National Organization for Women, said her group's focus would be on maintaining the current Supreme Court balance and ensuring that "we will not be the generation that both won and lost reproductive rights in our lifetime."

Abortions are becoming less common in the United States, particularly among teenagers, in part because of better contraception. The overall abortion rate fell from 1994 to 2000 -- from 24 abortions for every 1,000 women of childbearing age to 21 -- according to the nonprofit Alan Guttmacher Institute.

The Associated Press contributed to this report.