NEW YORK (AP) — Former Vice President Mike Pence filed paperwork on Monday declaring his campaign for president in 2024, setting up a challenge to his former boss, Donald Trump, just two years after their time in the White House ended with an insurrection at the U.S. Capitol and Pence fleeing for his life.

Pence, the nation's 48th vice president, will formally launch his bid for the Republican nomination with a video and kickoff event in Des Moines, Iowa, on Wednesday, which is his 64th birthday, according to people familiar with his plans. He made his candidacy official Monday with the Federal Election Commission.

While Trump is currently leading the early fight for the nomination, with Florida Gov. Ron DeSantis polling consistently in second, Pence supporters see a lane for a reliable conservative who espouses many of the previous administration’s policies but without the constant tumult.

While he frequently lauds the accomplishments of the “Trump-Pence administration,” a Pence nomination in many ways would be a return to positions long associated with the Republican establishment but abandoned as Trump reshaped the party in his image. Pence has warned against the growing populist tide in the party, and advisers see him as the only traditional, Reagan-style conservative in the race.

A staunch opponent of abortion rights, Pence supports a national ban on the procedure and has campaigned against transgender-affirming policies in schools. He has argued that changes to Social Security and Medicare, like raising the age for qualification, should be on the table to keep the programs solvent — which both Trump and DeSantis have opposed — and criticized DeSantis for his escalating feud with Disney. He also has said the U.S. should offer more support to Ukraine against Russian aggression, while admonishing “Putin apologists” in the party unwilling to stand up to the Russian leader.

Pence, who describes himself as “a Christian, a conservative and a Republican, in that order,” has spent months laying the groundwork for an expected run, holding events in early voting states like Iowa, South Carolina and New Hampshire, visiting churches, delivering policy speeches and courting donors.

Pence’s team sees Iowa and its evangelical Christian voters as critical to his potential path to victory. Advisers say he plans to campaign aggressively in the state, hitting every one of its 99 counties before its first-in-the-nation caucuses next year.

The campaign is expected to lean heavily on town halls and retail stops aimed at reintroducing Pence to voters who only know him from his time as Trump’s second-in-command. Pence served for more than a decade in Congress and as Indiana’s governor before he was tapped as Trump’s running mate in 2016.

As vice president, Pence had been an exceeding loyal defender of Trump until the days leading up to Jan. 6, 2021, when Trump falsely tried to convince Pence and his supporters that Pence had the power to unilaterally overturn the results of the 2020 election.

That day, a mob of Trump’s supporters violently stormed the U.S. Capitol building after being spurred on by Trump’s lies that the 2020 election had been stolen. Many in the crowd chanted “Hang Mike Pence!” as Pence, his staff and his family ran for safety, hiding in a Senate loading dock.

Pence has called Trump’s actions dangerous and said the country is looking for a new brand of leadership in the 2024 election.

“I think we’ll have better choices,” he recently told The Associated Press. “The American people want us to return to the policies of the Trump-Pence administration, but I think they want to see leadership that reflects more of the character of the American people.”

Pence has spent the 2 1/2 years since then strategically distancing himself from Trump. But he faces skepticism from both anti-Trump voters who see him as too close to the former president, as well as Trump loyalists, many of whom still blame him for failing to heed Trump’s demands to overturn the pair’s election defeat, even though Pence’s role overseeing the counting of the Electoral College vote was purely ceremonial and he never had the power to impact the results.

Pence joins a crowded Republican field that includes Trump, DeSantis, former United Nations Ambassador Nikki Haley, U.S. Sen Tim Scott of South Carolina, tech entrepreneur Vivek Ramaswamy, and former Arkansas Gov. Asa Hutchinson. Former New Jersey Gov. Chris Christie plans to launch his own campaign Tuesday evening in New Hampshire, and North Dakota Gov. Doug Burgum will announce his bid Wednesday in Fargo.

With Trump, a thrice-married reality star, facing skepticism among some Republicans during his 2016 run, his pick of Pence as a running mate assuaged concerns from evangelical Christians and others that he wasn’t sufficiently conservative. As vice president, Pence refused to ever criticize the former president publicly and often played the role of emissary, trying to translate Trump’s unorthodox rhetoric and policy proclamations, particularly on the world stage.

After Trump’s legal efforts to stave off defeat of the 2020 election were quashed by courts and state officials, he and his team zeroed in on Jan. 6, the date that a joint session of Congress would meet to formally certify President Joe Biden’s victory. In the weeks leading up to the session, Trump engaged in an unprecedented pressure campaign to convince Pence he had the power to throw out the electoral votes from battleground states won by Biden, even though he did not.

As the riot was underway and after Pence and his family were rushed off the Senate floor and into hiding, Trump tweeted, “Mike Pence didn’t have the courage to do what should have been done.” Video footage of the attack shows rioters reading Trump’s words aloud and crowds breaking into chants that Pence should be hanged. A makeshift gallows was photographed outside the Capitol.

Pence has said that Trump “ endangered my family and everyone at the Capitol that day” and that history will hold him accountable.

Despite his harrowing experience, Pence opposed efforts to testify in investigations into Trump’s actions on and in the lead-up to Jan. 6. He refused to appear before the House committee investigating the attack and fought a subpoena issued by the special counsel overseeing numerous Trump investigations, though he did eventually testify before a grand jury.

Only six former U.S. vice presidents have been elected to the White House, including Biden, who is running for a second term.