Mike Pence Is Running for President Against Trump. Here’s What to Know.

Over the past eight years, Mike Pence has gone from being a skeptic of Donald J. Trump to his doggedly loyal vice president to the target of his strongest supporters during the Jan. 6, 2021, attack on the Capitol. Now he is one of a growing number of Mr. Trump’s opponents in the Republican presidential primary.

Mr. Pence was elected the governor of Indiana in 2012 after six terms in the House of Representatives, where he became the chairman of the Republican conference, the third-highest position in House Republican leadership. He dropped his campaign for re-election as governor when Mr. Trump named him as his running mate in 2016.

Here are five things to know about Mr. Pence.

He was perhaps the most loyal Trump loyalist.

Before Mr. Trump was nominated in 2016, Mr. Pence — like many Republicans — was critical of him. Among other things, in 2015, he called Mr. Trump’s suggestion to bar Muslims from entering the United States “offensive and unconstitutional.”

But once Mr. Pence agreed to be Mr. Trump’s running mate, he went all in. Though he said in 2016 that he would not be Mr. Trump’s “cleanup crew,” he eventually became Mr. Trump’s most reliable defender, regularly called on to explain or spin controversies, advise cabinet secretaries and lawmakers and provide a more traditional and religious conservative veneer to the candidate and president.

He stayed on the ticket in October 2016 after the release of the “Access Hollywood” recording in which Mr. Trump bragged about assaulting women. He stood by Mr. Trump through the Robert S. Mueller investigation and Mr. Trump’s first impeachment. He was so loyal that the vice-presidential historian Joel K. Goldstein called him the “sycophant in chief.”

At points, the commitment was reluctant — most strikingly in the case of the “Access Hollywood” tape. A Politico report in 2019 described Mr. Pence’s reaction: He told advisers he wasn’t sure he could stay on the ticket, and then cut off contact with the campaign while he deliberated, even failing to show up to a rally he had been scheduled to attend. His wife, Karen Pence, told him she wouldn’t appear in public if he stuck with Mr. Trump.

He did. And in doing so, he put himself in position for his own presidential run.

“They’re thinking about running in 2020 in their own right because they don’t expect that Donald Trump is going to win,” Tom LoBianco, a reporter who wrote a biography of Mr. Pence, told NPR, describing the Pence team’s calculations in 2016.

But Mr. Trump did win in 2016, so the focus turned to 2024. Never wanting to alienate the leader of the party whose nomination he coveted, or the Republican voters whose allegiance was clear, Mr. Pence studiously ignored policies and behaviors that he could not defend.

But he reached his limit on Jan. 6.

More than four years of subservience ended on Jan. 6, 2021, when Mr. Pence fulfilled his constitutional obligation to certify the Electoral College votes from the 2020 presidential election.

In doing so, he defied weeks of pressure from Mr. Trump to overturn the election results himself, or send the electoral slates back to state legislatures so they could overturn them, based on false claims of election fraud. He also made a permanent enemy of a large portion of the Republican base.

He later condemned Mr. Trump’s incitement of the attack on the Capitol, which was led by a mob that tried to stop the certification and chanted, “Hang Mike Pence.”

“The president’s words that day at the rally endangered me and my family and everyone at the Capitol building,” he told ABC News in November. It is a sentiment he has repeated multiple times since then — including at the annual Gridiron Club dinner in March, where he declared that “history will hold Donald Trump accountable.”

At the same time, Mr. Pence sought to avoid testifying in investigations of Mr. Trump’s actions. In early April, after a protracted legal battle, he said he would not appeal a ruling forcing him to testify to a grand jury. He testified on April 27.

He underwent two major conversions early on.

Mr. Pence was raised in a Roman Catholic and Democratic family, and voted for Jimmy Carter in 1980. But he broke from both affiliations, becoming an evangelical Christian in college and then a conservative Republican. He has said his religious conversion was driven by a longing for a more personal relationship with God.

He has described his religion as informing every aspect of his life — he refuses to eat alone with women other than his wife and, when he was in Congress, allowed only male aides to work late with him — and his politics, especially his opposition to abortion.

Mr. Pence also opposes gay marriage and has suggested that Obergefell v. Hodges, the Supreme Court ruling that legalized it nationally, conflicts with religious freedom. In Congress, he voted against employment nondiscrimination protections for gay people, and, like many other Republicans, has described the affirmation of transgender students as “radical gender ideology.”

In 2015, as the governor of Indiana, he drew national attention for signing the Religious Freedom Restoration Act, which prompted outrage at the possibility that business owners would be empowered to refuse service to L.G.B.T.Q. people. Taken aback by the strength of the backlash, Mr. Pence and Republican legislators amended the law to say it did not authorize such discrimination, a retreat some Christian conservatives saw as a setback.

He favors a federal abortion ban and would grant fetuses legal “personhood.”

As a congressman, Mr. Pence led the first major federal effort to defund Planned Parenthood. As the governor of Indiana, he signed every anti-abortion bill that reached his desk, including one in 2016 that banned abortions based on the fetus’s race, gender or disability and required fetal remains to be cremated or buried. (A judge blocked it, and the Supreme Court declined to reinstate the ban but upheld the cremation or burial mandate.)

And today, Mr. Pence is one of the few prominent Republicans maintaining a hard public line on abortion after the backlash to the Supreme Court’s Dobbs ruling made that a clear liability in general elections.

He has said abortion opponents “must not rest” until it is banned nationwide, and criticized a suggestion from Mr. Trump that abortion policy should be left to states. His political organization, Advancing American Freedom, has endorsed federal bills to ban abortion after about six weeks — before many people know they are pregnant — and to establish fetal personhood, which would confer legal rights starting at fertilization and make abortion illegal with no, or almost no, exceptions.

He was also among the only presidential candidates to praise a Texas judge’s ruling (temporarily blocked by the Supreme Court) invalidating the Food and Drug Administration’s 23-year-old approval of the abortion pill mifepristone. “I fully support efforts to take the abortion pill off the market,” he told a local Fox station in California.

His responses to public health crises have been scrutinized.

In 2015, Mr. Pence faced a crisis in Scott County, Ind., where H.I.V. was spreading explosively among intravenous drug users. For weeks, he resisted health officials’ calls for a program that would supply clean needles, a policy he opposed on the basis that it would enable drug abuse.

The New York Times reported in 2016 that Mr. Pence’s staff was initially unwilling to discuss a needle exchange program, or to engage with scientific evidence that such programs reduce the risk of infections without increasing drug use.

After extensive pressure, Mr. Pence changed course. (“I’m going to go home and pray on it,” he told his health commissioner shortly before relenting.) Once authorized, the needle program quickly brought the outbreak under control. Around 200 people had been infected, a number that could have been lower with an earlier response.

This episode drew renewed scrutiny in 2020, when Mr. Trump put Mr. Pence in charge of the government’s handling of the coronavirus. The job — leading a pandemic response for an administration that was actively trying to avoid leading a pandemic response — was unenviable. Mr. Pence’s task was often to clean up after Mr. Trump’s misinformation, and he provided some inaccurate information of his own.

He argued in his memoir “So Help Me God” that the response had been successful. “I know we saved millions of lives,” he wrote, though the United States had a higher death rate from Covid than most other developed countries — a bleak distinction that continued under President Biden.