WASHINGTON — Vice President Mike Pence was doing just fine in the background. Then a Democrat called him “decent.”
In their search to present themselves as the antidote to the Trump administration, a raft of Democratic presidential hopefuls are targeting Mr. Pence, an evangelical Christian and comparatively sedate figure who has showcased President Trump’s hard-line policies to the rest of world with a smile.
But a compliment last month from Joseph R. Biden Jr., the former vice president on the verge of announcing his own candidacy, thrust Mr. Pence into the 2020 conversation.
After Mr. Biden referred to him during a speech as a “decent guy,” several Democrats lined up to say the opposite:
Senator Elizabeth Warren of Massachusetts said in an interview with MSNBC that Mr. Pence was “not an honorable person.”
Senator Kamala Harris of California said that she found it “outrageous” that Mr. Pence refuses to take meetings with any woman who is not his wife, a claim his office denied.
And Mayor Pete Buttigieg of South Bend, Ind., a long-shot presidential contender, said last week in a CNN town hall that Mr. Pence, a former governor of Indiana with whom Mr. Buttigieg used to work, had “become the cheerleader for the porn star presidency.”
Mr. Biden eventually walked his compliment back.
Lightning Rod is a new role for Mr. Pence, who has so far perfected his good-cop appearance. On Friday, as Mr. Trump issued the first veto of his presidency, rejecting legislation that opposed his declaration of a national emergency to fund a wall along the southwestern border, the vice president was there to heap praise.
“I don’t know that I’ve ever been more proud,” Mr. Pence told Mr. Trump, “than to be standing next to you today.”
But his willingness to stand behind the president, coupled with the assault on his beliefs by Democratic candidates, has only further highlighted a key truth about Mr. Pence: He is less a good cop than he is a good soldier.
“It’s possibly the case that just because the show has become so mesmerizing, there hasn’t been enough attention for there to be scrutiny on him and what he represents,” Mr. Buttigieg said. “But there’s a nontrivial chance of Pence becoming the president, any day, and we should understand what we’re getting there.”
Mr. Buttigieg said that Mr. Pence was a politician “whose views are very much out of the mainstream.” He ticked off issues like gay marriage (Mr. Pence has said he is opposed to it); climate change (Mr. Pence has said the causes of it remain to be seen); and evolution (Mr. Pence has said God created heaven and earth) as policy issues on which the vice president needed to clarify his positions.
Mr. Pence declined to comment publicly, but a senior administration official familiar with his thinking said he does not plan to take the bait. “He just lets the criticism roll off,” said that official, who spoke on the condition of anonymity so as to not disclose private conversations.
But Mr. Biden, who is seen in the White House as Mr. Trump’s most formidable potential 2020 challenger, earned a public rebuke from the vice president.
“Well, look, they’ve got an awfully big field,” Mr. Pence said on Thursday in an appearance on “Fox & Friends,” adding that “the way Joe Biden caved in to liberal activists after making a kind comment for me is evidence of the pressure that all of their candidates are going to face.”
Still, some observers of the race say the scrutiny of Mr. Pence may continue.
“I’m surprised he hasn’t been in the middle of it more,” said Tim Miller, a longtime Republican strategist and a “Never Trumper.” “He’s skillfully avoided, to a certain degree, the amount of association he should have with Trump.”
But Mr. Miller said the backlash to Mr. Biden’s comment also “reinforces what a lot of Republicans would say, which is the fact that no matter who the Republican nominee or president or vice president would be, the Democrats would demagogue him.”
Hilary Rosen, a Democratic political strategist, said that Mr. Pence is a smaller target than Mr. Trump, but his conservative politics present a punch list for liberal voters.
“The issues Pence is most identified with,” Ms. Rosen said, “are ones that a majority of voters, including independents, strongly support. So he will be vulnerable.”
Since becoming vice president, Mr. Pence has done little to clarify his beliefs, but his office has pushed back on some of the more enduring assertions about them, like the claim by Ms. Harris that he would not take meetings alone with women.
That criticism stems from a 2002 interview in which Mr. Pence, then a congressman from Indiana, said that he did not dine with women who were not his wife, Karen.
“He absolutely meets with women,” Alyssa Farah, Mr. Pence’s spokeswoman, said on Friday. “That’s just not the case.”
Some Democratic candidates are also hoping to seize on Mr. Pence’s track record on gay rights, and have pointed to several examples as fodder for what they think are restrictive and harmful policy decisions.
Privately, Mr. Pence and his aides have tried to signal that his views on gay rights are not as extreme as critics have said, and at least one defender in the Trump administration has spoken publicly in support: Richard Grenell, the United States ambassador to Germany, who recently announced an initiative to decriminalize homosexuality worldwide.
“For those of us in the LGBT community who deal in facts, we are chilled by recklessly repeated gossip,” Mr. Grenell wrote on Twitter. “Mike Pence is a humble Christian who loves God, and all His creation. I know him. You obviously don’t.”
Mr. Buttigieg, who is gay, said that he and other Democrats would welcome an explanation from Mr. Pence.
“Until he does,” Mr. Buttigieg said, “I don’t think anybody’s going to be convinced that he’s moderated or become any less extreme.”