Mrs. Pence’s sudden transformation, her participation in Trump campaign events and her gushing praise of the president stems from a desire to protect her husband’s political future and to fiercely defend him in an election contest that seems to get uglier by the day, according to eight current and former administration officials and people close to the Pence family who spoke to POLITICO on the condition of anonymity.

The arrangement is also mutually beneficial: The vice president maintains his popularity with Trump’s religious conservative base, while the campaign gains a notable surrogate who can speak directly to the suburban women currently trending away from the president.

“Mrs. Pence is no stranger to campaigning, and is looking forward to being on the campaign trail for the 2020 presidential election,” Kara Brooks, a spokeswoman for Mrs. Pence, said in a statement.

“Her participation in campaign events, such as Women for Trump, are opportunities to highlight the great accomplishments of the administration. She also gets a chance to share information about her military spouse awareness campaign and art therapy initiative,” Brooks added.

It could be the greatest political challenge Mrs. Pence has faced, as Trump gets hit from all sides during the constant drip of impeachment news and foreign policy flare-ups tied to Ukraine and Syria. The second lady’s unscathed image and relatively low profile to date — her family’s pet rabbit, Marlon Bundo, has 12 times more Instagram followers than she does — gives her a clean slate of sorts to make her case on behalf of Trump and her husband to voters who may be skeptical of the duo heading into 2020.

It also comes as she and the vice president aim to restore their image as faithful foot soldiers for the Trump agenda following the release of separate books this summer, by journalists Tim Alberta of POLITICO and Tom LoBianco, that detailed a pair of episodes in which Mrs. Pence refused to kiss her husband on election night and vowed not to appear on the campaign trail beside him if he carried on as the president’s running mate after the “Access Hollywood” tape emerged.

“Oh boy. Mother is not going to like this,” Pence told aides at the time, anticipating his wife’s reaction to the audio recording of Trump’s lewd comments, Alberta wrote in his book.

But that attitude was hardly on display last week, when Mrs. Pence hit the campaign trail for her first appearance at a “Women for Trump” event. In fact, nowhere was her embrace of the president more palpable. The second lady, whom Trump directly apologized to after the “Access Hollywood” scandal first broke, told attendees of the event in St. Paul, Minn., she was “all in” for the president after seeing him interact with her daughter, Charlotte.

Appearing alongside presidential daughter-in-law Lara Trump and campaign spokeswoman Kayleigh McEnany, she also urged the crowd to “get on your knees” to pray for the president.

Asked about her remarks, one of the vice president’s former House colleagues said it was characteristic of Pence’s wife, who defended him through his stints as chairman of the staunchly conservative Republican Study Committee, Republican conference chair and Indiana governor before he joined the GOP presidential ticket in 2016.

“Karen knows a lot about campaigns, she knows a lot about politics and she knows what she’s in for, and she likes to practice it at a very high level of competition,” the former colleague said. “She knows they’re in for the fight of their life right now as part of the ticket and she does not shirk away from that responsibility.”

Campaign officials said the Minnesota event was the first of many appearances Mrs. Pence will make in the coming months, in addition to doing local radio and television while traveling. The second lady, whose husband hosted a conservative radio program in the 1990s, did a series of interviews on radio row ahead of Trump’s June 2020 kick-off rally in Orlando, Fla., which one official described as “a natural fit” for her.

Until now, Mrs. Pence’s solo travel has typically been linked to her art therapy initiative, an issue she has worked closely on since 2011, or support for military spouses.

“I want to get more people aware of art therapy, not only for children who are going through an illness, but adults as well who have gone through trauma,” Mrs. Pence, a watercolorist who has illustrated two children’s books with her daughter, Charlotte, told The New York Times in a 2017 interview.

With the exception of an appearance she made shortly before last year’s midterm elections on behalf of congressional candidate Mark Harris (the North Carolina Republican later abandoned his effort to win the seat following revelations that his campaign had become entangled in a voter fraud operation), Mrs. Pence has mostly traveled with her husband on his diplomatic missions and domestic trade tours. Just last month, she accompanied him on his trip to Poland, where Pence met with Ukrainian President Volodymyr Zelensky. That meeting has come under scrutiny as Democrats work to determine whether the vice president was aware of the pressure campaign that landed Trump at the center of an impeachment inquiry in the House of Representatives.

A spokeswoman for Mrs. Pence said she did not join her husband on Wednesday when he left for Turkey, where he and Secretary of State Mike Pompeo will meet with President Recep Tayyip Erdogan in an effort to negotiate a ceasefire in northeastern Syria.

Officials familiar with the planning said the vice president’s built-in team on the 2020 campaign is currently devising a messaging strategy and schedule that maximizes the couple’s strengths as surrogates — including dispatching Mrs. Pence, a Kansas native, to suburban swing districts and Midwestern battleground states to tout the administration’s work on healthcare, education and pro-family policies.

“The 2016 staff didn’t know how to utilize Karen Pence, but now there’s a VP staff that knows her. You look at her experience of being a mother of three, of being a wife of someone who’s been in the public eye for 30 years and you’ll hear about anything from her that really goes back to family issues and stuff that’s important to women,” said the GOP source familiar with Trump’s reelection operation.

This person added that Mrs. Pence will likely be deployed to “suburban media markets” and that communities outside of “Atlanta, Houston, Dallas [and] Detroit would be really good for her.”

She is also expected to highlight the president’s track record of selecting conservative judges for appellate and circuit court appointments — an issue that resonates with the same white evangelical voters who Pence helped put at ease when he was added to the ticket in 2016.

“Particularly with the faith community, Karen is a very capable emissary,” said the former House colleague.

It’s unclear if a ramped-up campaign schedule will affect Mrs. Pence’s part-time teaching position at Immanuel Christian, a private K-8 school just outside of Washington. The 2020-2021 school year would likely begin next August, right after both parties host their nominating conventions and months away from the November election. Brooks declined to respond to a question about Mrs. Pence’s tenure at the school, while a campaign official said there have been “no discussions on whether she’ll leave Immanuel Christian to make herself more available to the campaign.”

The anticipated increase in Mrs. Pence’s campaign activity comes as the vice president faces the most significant test yet of his loyalty to Trump, whose attempt to use his relationship with a foreign leader to conjure up dirt on 2020 presidential hopeful Joe Biden led House Speaker Nancy Pelosi to endorse an impeachment investigation last month. Pence, who’s sought to avoid being implicated in any wrongdoing by denying that he was aware of the president’s overtures to Zelensky, recently launched a nationwide tour to swing districts occupied by Democrats who have endorsed the impeachment probe.

Trump has previously said he no longer questions the loyalty of the Pences. Last November, he told reporters his vice president has “already been tested, in many ways [and] I could not be happier,” and at the annual National Prayer Breakfast in February, he praised Mrs. Pence as “a Marine Corps mom, a tremendous woman, [and] a proud supporter of military families.”

But the president’s odd comments last month about Pence’s own interactions with Zelensky suggested to some observers that Trump remains wary of his vice president’s political ambitions.

It’s that constant question of loyalty that led Mrs. Pence to ask for a more pronounced role in the campaign than she ever wanted three years ago, according to two people close to the Pence family, one of whom said staffers on the 2016 campaign had mixed feelings about the future second lady. One former campaign aide said she could be controlling and often yielded more influence over Pence than the campaign's most seasoned political advisers — much to their chagrin.

But others, including those who worked closely with Mrs. Pence and the vice president, said she was always reminding them not to neglect their families, who she asked about frequently.

“She uniquely understands the impact public service has on those around you and would be the first one to say if you had an anniversary or a birthday or something coming up, ‘You make sure you go home,’” said a former administration official, who recalled that Mrs. Pence would often sneak fresh fruit and vegetables into the overhead bins on the campaign plane Pence used for travel in 2016 after she noticed “we were filling up on junk food.”

The GOP source familiar with Trump’s reelection operation added that Pence’s wife, who campaigned alongside her husband at county fairs during his third congressional bid in 2000, will be an asset to the campaign simply because “she loves her country.”

“But what it really comes down to,” this person said, “is that she loves her husband and wants to help him in any way she can.”