During a recent appearance in South Carolina, after Ron DeSantis played up his state’s economic and education policies and bashed a litany of ideological adversaries, his wife settled into an armchair next to him onstage, reflecting on her role as the first lady of Florida.
“I didn’t want to be that proverbial potted plant,” Casey DeSantis said.
No one — fan, skeptic or critic — would accuse her of that.
Ms. DeSantis, 42, is widely seen as perhaps Mr. DeSantis’s most important adviser. In the governor’s mansion, she advised on media strategy and helped vet personnel. She has narrated some of his more attention-grabbing ads and taken on wide-ranging projects about issues like mental health, disaster relief and cancer, surviving a bout with it herself.
Now, as Mr. DeSantis enters the presidential contest, people who know Ms. DeSantis or who have encountered her on the nascent campaign trail expect that she will play a vital role in his most important race yet, seeking to shape perceptions of the campaign, build relationships with party stakeholders and to illuminate the personal side of her hard-edged husband, who sometimes struggles to connect.
“You have the first ladies that are kind of more in a supportive posture, they are not ones that are out there stumping,” said Steven Wright, the Republican chairman in Dorchester County, S.C., who encountered Ms. DeSantis during the couple’s swing through the area. “And then you have the first ladies that are similar to Casey DeSantis.”
In recent weeks, she has gushed over Iowa’s gas station pizza and highlighted her personal connections to South Carolina, the first-in-the-South primary state (she attended the College of Charleston, where she competed on the equestrian team).
She has met with local Republican officials and offered public glimpses of family life as the mother of three children. When Mr. DeSantis spoke at a Republican dinner in Ohio last month, Ms. DeSantis joined the trip too, swinging through her hometown, Troy, Ohio, where the family met with the mayor.
“She shows the human side of the governor and his personal side,” Mr. Wright said.
And she and Mr. DeSantis recently hosted Bob Vander Plaats, an influential social conservative from Iowa, for lunch at the governor’s mansion.
“They could free her up to go on her own to represent the governor at different campaign stops where he can’t be,” said Mr. Vander Plaats, citing her “ability to be very poised in front of a crowd.” He recalled that they dined on arugula spring salad, prosciutto-wrapped scallops with green beans and a strawberry fruit salad dessert.
Mr. DeSantis met Jill Casey Black, a local news reporter at the time, at a driving range complex in Florida, he wrote in his recent book, “The Courage to Be Free.” They were married at Walt Disney World, years before Mr. DeSantis went to war with Disney. (“Casey’s family was what one might call a family of Disney enthusiasts,” he wrote.)
Casey DeSantis built a career as a television personality in Florida, though that background has not stopped her from echoing Mr. DeSantis in lashing the “woke corporate media.”
“She’s keenly aware of public-facing events, the news cycle, optics,” said Stephen Lawson, who served as Mr. DeSantis’s spokesman during his 2018 race for governor. “So much of who he is and where he’s come from and his story centers around her, and I think she’ll continue to play a pivotal role in how that story unfolds.”
“She is his primary sounding board,” he added.
In that 2018 contest, she narrated an ad that highlighted Mr. DeSantis’s fealty to President Donald J. Trump by showing him encouraging his young child to “build the wall” out of blocks.
Last year, she recorded an emotional direct-to-camera spot, her voice wavering as she described how her husband had helped her through cancer.
She also promoted a video that cast his political rise as divinely inspired.
Ms. DeSantis has also been linked to political drama, and some have questioned the scope of her portfolio in office, wondering whether she has too much influence inside the governor’s insular inner circle.
“She assumes authority that she does not have,” said Mac Stipanovich, a Republican-turned-independent who served as a longtime Florida strategist and lobbyist, though he said he was sharing his impressions rather than firsthand knowledge. “From whence came this woman’s strategic political genius?”
“People would always question, who is the closest person to Ron, who is somebody who can get his ear?” added Nikki Fried, now the chairwoman of the Florida Democratic Party and a former agriculture commissioner who ran unsuccessfully for governor in the Democratic primary last year. The only name that ever came back, she said, “was Casey’s.”
Lindsey Curnutte, a spokeswoman for the DeSantis team, did not respond to a request for comment.
But Representative Jared Moskowitz, a Florida Democrat who worked with the DeSantises as Florida’s director of emergency management, said he had found Ms. DeSantis to be someone who was receptive to ideas and whose “door was always open.”
“The first lady, who has a significant background in communications, comes into a room and really just captivates,” said Mr. Moskowitz, who is supporting President Biden’s re-election bid.
There is a long history of politicians navigating the complexities of family members’ involvement in their campaigns or administrations, including Bill and Hillary Clinton and Vice President Kamala Harris, whose sister was a key adviser during her presidential primary campaign.
In New York City, Chirlane McCray was the closest adviser to her husband, Bill de Blasio, as he ran for mayor and then during his time at City Hall, an arrangement that at times stoked controversy.
In an interview, Mr. de Blasio — a Democrat who is “energetically” supporting Mr. Biden — defended the art of the political power couple, saying that “when it feels natural, it’s kind of irreplaceable.”
“You need someone who understands your goals, your motivations, what you can handle, what you can’t, all that, and that’s all subsumed in a spouse under good conditions,” Mr. de Blasio said.
But he acknowledged that, depending on the couple, spouse-advisers could also be “too close to the situation.”
“There’s a huge tradition of spouses being very protective and defensive for their loved one in office,” he said. “Sometimes that can create a blindness or a kind of knee-jerk reaction, or a sense of vengeance that is not always productive.”
“It can be a beautiful model, it can be a powerful model,” he added, “or it can really backfire.”
Nicholas Nehamas contributed reporting. Kirsten Noyes contributed research.