WASHINGTON — Vice President Mike Pence has been a metronome of consistency in providing dutiful affirmation for President Trump. He nods approvingly. He claps enthusiastically. He defends vigorously.
So it was highly unusual when Mr. Pence broke with form this week, actually getting out front of the president and praising a concurring opinion by Justice Clarence Thomas in a case in which the Supreme Court refused to hear an appeal seeking to reinstate an Indiana law banning abortions sought solely because of the sex or disability of a fetus.
The case involved a law that Mr. Pence had signed as governor, but he was uncharacteristically outspoken.
“Today, Justice Thomas wrote: SCOTUS has been zealous in the past in barring discrimination based on sex, race, & disability,” he said, taking to the president’s preferred medium, Twitter. “Hopeful someday soon SCOTUS will recognize the same protections for the unborn when they rule on future appeals of pro-life legislation.”
In what appeared to be a compromise by the justices, they also upheld a part of the Indiana law that requires abortion providers to bury or cremate fetal remains. Mr. Pence tweeted approvingly about that action by the court.
“As Governor of IN I was proud to sign a law that requires remains of aborted babies be treated w/dignity & respect and blocks groups like Planned Parenthood from the horrific practice of selling fetal tissue,” he said. “Today’s decision by the Supreme Court was a victory for life!”
It is rare for any vice president to make such high-profile comments on a Supreme Court case. But Mr. Pence’s quick endorsement of Justice Thomas’s concurrence was just another measure of how important the abortion issue is to him personally as well as politically.
Mr. Trump has increasingly emphasized his opposition to abortion as the 2020 presidential campaign enters a more energetic phase, and as many of his would-be Democratic challengers warn of the threat to abortion rights posed by both a conservative Supreme Court and state legislatures like Alabama’s. On Wednesday, the president implored supporters in Alabama, which recently passed one of the nation’s most restrictive abortion laws, to reclaim a seat lost to Senator Doug Jones, a Democrat.
“If Alabama does not elect a Republican to the Senate in 2020, many of the incredible gains that we have made during my Presidency may be lost, including our Pro-Life victories. Roy Moore cannot win, and the consequences will be devastating,” he said on Twitter, adding, “Judges and Supreme Court Justices.”
Even with a relatively strong economy — though there have been some warning signs of late — the president has continued to highlight cultural issues, and none more than abortion.
In recent weeks, he has been reprising a line used in his third presidential debate with Hillary Clinton, saying that supporters of expanded abortion rights favored permitting a baby to be ripped “out of the womb of the mother just prior to the birth of the baby.”
The battle over abortion that is playing out in a number of states, in most cases reflecting the red-blue divide in the country — amplified by Mr. Trump, the vice president and the Democratic candidates — ensures that it will be among the animating issues of the presidential campaign.
But while Mr. Trump may be the louder voice on the issue, Mr. Pence’s is the one many evangelicals hear. Mr. Pence has been Mr. Trump’s bridge to the white, conservative evangelical community that has provided a durable foundation for the president’s support that is also essential to his prospects for a second term.
Richard Land, the president of Southern Evangelical Seminary in Charlotte, N.C., said that he was asked by the Trump campaign in 2016 what advice he had for winning over evangelical voters, and had a ready answer. “I said, Pick Mike Pence,” Mr. Land said in a recent interview. “Because there is no way you could signal more clearly to evangelicals that they had a seat at the table than in picking Mike Pence. He is the 24-karat-gold standard.”
Mr. Pence brought both a different résumé and a different temperament to Mr. Trump’s team. He had deep experience in government and is not given to the president’s florid language. And he served as a potent validator for Mr. Trump among his base on abortion and other conservative social issues.
Mr. Trump had been on both sides of the abortion issue. As recently as 1999, he had said in a television interview that he was “very pro-choice.” There was no such ambiguity in Mr. Pence’s record.
Nor is there any now. Mr. Pence has spoken at the annual March for Life rally of anti-abortion activists, the first vice president to do so, while Mr. Trump appeared on a video. The march was the rare moment when the vice president was the headliner at an event where the president was also a presence.
He has criticized Roe v. Wade, the Supreme Court decision that made abortion legal, saying the court at the time had “turned its back” on the right to life.
“We’re the Pences, and we’re pro-life,” he said, standing with his wife, Karen. “We gather here because we stand for life.”
That stance has extended beyond the United States. After a meeting in Ottawa on Thursday, Justin Trudeau, the Canadian prime minister, said he told Mr. Pence that there was significant concern about a “backsliding” of women’s rights and new “anti-choice laws” being passed in the United States.
“It was a cordial conversation,” Mr. Trudeau said, “but it is one of which we have very different perspectives.”
But Mr. Pence was not moved. “Let me be clear,” he said. “I’m very proud to be part of a pro-life administration.”