WASHINGTON (AP) — Former Vice President Mike Pence used a Friday gathering of some of the nation’s leading Christian conservatives to urge his rivals for the Republican presidential nomination to support a 15-week federal abortion ban at minimum.

The exhortation at the Faith & Freedom Coalition’s annual conference, coming a day before the first anniversary of the Supreme Court decision that overturned Roe v. Wade, amounted to a challenge for the GOP front-runner, Donald Trump, who has been reluctant to endorse a federal abortion ban. The former president is addressing the evangelical assembly on Saturday night.

“We must not rest and we must not relent until we restore the sanctity of life to the center of American law in every state in this country,” Pence said. “Every Republican candidate for president should support a ban on abortion before 15 weeks as a minimum nationwide standard.”

Pence was among a number of 2024 Republican presidential hopefuls — including Florida Gov. Ron DeSantis and Sen. Tim Scott of South Carolina — to speak Friday before a ballroom of about 500 attendees. All of the candidates emphasized their anti-abortion credentials while urging like-minded activists to stay on the political offensive, even as leading Democrats insist their party’s defense of abortion rights will be a 2024 boon to them.

DeSantis, who signed a law in Florida banning abortions after six weeks of pregnancy, touted the measure with a nod toward Trump’s veiled criticism last month that it is “too harsh.”

“It was the right thing to do,” DeSantis told the crowd. “Don’t let anyone tell you it wasn’t.”

DeSantis has been less clear on where he stands on a federal abortion ban.

Not far from the conference site in Washington, President Joe Biden and Vice President Kamala Harris were rallying Friday with abortion rights supporters to mark the anniversary of the Dobbs v. Jackson Women’s Health Organization decision.

That ruling, issued June 24, 2022, ended federal constitutional abortion protections and paved the way for near-total bans in some Republican-led states. Democrats have vowed to codify the right to an abortion in federal law, but don’t have the votes in Congress to do so.

“Since that dark June day last year, each one of you has worked tirelessly to fight back,” Biden told activists from reproductive rights groups. “You ain’t seen nothing yet.”

Referring to supporters of Trump’s Make America Great Again movement, the president added, “What’s really remarkable is despite the will of the American people, MAGA Republicans made it clear that they won’t stop with the Dobbs decision.”

After stronger-than-expected results in last year’s midterm elections, Democrats believe issues surrounding abortion access can energize their base, attract moderates alienated by GOP hardliners and help the party hold the Senate, flip the House and reelect Biden

Even Trump has suggested that increased abortion restrictions are a weakness for Republicans, despite his three Supreme Court nominees making up the majority of justices who voted to overturn Roe last year.

He posted on his social media site in January that the party’s underwhelming midterm performance “wasn’t my fault” and blamed “’the ​’abortion issue,​’​ poorly handled by many Republicans, especially those that firmly insisted on No Exceptions, even in the case of Rape, Incest, or Life of the Mother.”

Yet the mood at Friday’s Faith & Freedom Coalition session was jubilant, with attendees cheering every mention of Roe v. Wade’s reversal. “Thank God almighty for the Dobbs decision,” Scott told the crowd.

Ralph Reed, founder and chairman of the Faith & Freedom Coalition, said the conference’s dates were set years ago, so the fact that it spans the Dobbs anniversary is a “serendipitous coincidence.” Still, he said the gathering is out to ensure top Republican candidates don’t get complacent when it comes to opposing abortion.

“We’re certainly going to do everything that we can, as an organization and as a pro-life and pro-family movement, to give our candidates a little bit of a testosterone booster shot and explain to them that they should not be on the defensive,” Reed said in an interview before the conference began. “Those who are afraid of it need to, candidly, grow a backbone.”

Reed drew sustained cheers when he opened the gathering by saying that “after 50 years of prayer, and fasting and knocking on doors and electing candidates and registering voters and changing the culture of our country, Roe v Wade has been overturned.”

Michigan Sen. Gary Peters, head of the Democrats’ Senate campaign arm, said this week that top Republican presidential candidates will back a nationwide ban to win support in their GOP primaries, then shift to a more moderate position for the general election.

“They’re not going to get away with that,” Peters said.

Among GOP candidates, Pence has previously said he’d support banning abortion nationally after just six weeks of pregnancy, before many women know they are pregnant.

His declaration Friday that a ban at 15 weeks should be the “minimum nationwide standard” mirrors a call from the anti-abortion group Susan B. Anthony Pro-Life America. The organization has vowed not to support any White House candidate who doesn’t support a 15-week federal ban at a minimum.

Scott also has praised South Carolina’s six-week ban and backs a 15-week federal prohibition. Former U.N. Ambassador Nikki Haley supports a federal ban but hasn’t said at what point in pregnancy she would seek to ban abortions.

Trump has avoided specifying what national limits, if any, he would support on abortion.

A deeply devout, evangelical Christian, Pence was greeted far more warmly at this year’s Faith & Freedom Coalition conference than he was the last time he addressed the group in 2021. Then, he was booed by some and faced shouts of “traitor.” That event, held in Florida, came months after the Jan. 6 insurrection at the U.S. Capitol, when Pence defied Trump’s unprecedented demands to overturn Biden’s victory in the 2020 election.

The tamer reaction came after Reed warned Friday’s audience about booing or verbally expressing disagreement with any presidential candidates: “If they’re not where they need to be, then let’s just love them and pray them right where they need to go.”

Not everyone heeded that warning. Former New Jersey Gov. Chris Christie, who has built his 2024 candidacy around criticizing Trump, drew boos when he said the former president is more interested in promoting himself than the country’s interests.

A woman near the stage bellowed “We love Trump” and a few others tried to start chants of “Trump! Trump! Trump!” but Christie was able to finish his speech.

“You can boo all you want but here’s the thing, our faith teaches us that people have to take responsibility for what they do,” said Christie, who is Catholic. “People have to stand up and take accountability for what they do.”