WEST BLOOMFIELD, Mich. — With Joseph R. Biden Jr. expected to announce his choice of running mate in the coming days, Gov. Gretchen Whitmer of Michigan has suddenly joined the pack of leading contenders in the home stretch — a turn that has some Democrats in the state excited, but has left others concerned about how they, and Michigan, might fare without her.
Talk of her 11th-hour political momentum began after she took a secretive, chartered flight to Delaware from Lansing, Mich., this month for a two-hour conversation with Mr. Biden, a trip first reported by The Associated Press.
That Ms. Whitmer, a well-regarded Democratic governor of a battleground state, could vault into the top circle of contenders shows just how fluid Mr. Biden’s selection process has been — but it also illustrates the complex considerations involved in choosing a running mate based on her record during a crisis, one that shows no sign of ending soon.
Ms. Whitmer’s spokeswoman, Tiffany Brown, declined to comment on the vice-presidential speculation or her boss’s travel schedule.
While much of the attention around Mr. Biden’s impending decision has focused on the energy that high-profile candidates like Senator Kamala Harris of California could bring to the campaign, Ms. Whitmer’s supporters say that her response to the coronavirus in Michigan makes her an appealing running mate for a contender looking to contrast himself with President Trump.
“I think she deserves it and she’d be phenomenal,” said Barry Goodman, a lawyer who sits on the finance committees for the campaigns of both Ms. Whitmer and Mr. Biden.
Rosemary Bayer, a Democratic state senator from Beverly Hills, outside Detroit, praised Ms. Whitmer’s handling of the pandemic.
“When you look at what she’s done here, she’s actually gotten things done to deal with the Covid crisis,” she said. “And given the gap we have in leadership now, she would be a really, really good choice.”
During the pandemic, Ms. Whitmer became a frequent guest on cable and network news shows and a vocal critic of Mr. Trump’s response to the crisis. In a half-dozen polls taken since the virus shut down Michigan in March, she has received consistently high approval ratings, ranging from 57 percent to 63 percent, compared with Mr. Trump, whose ratings in Michigan have been stuck in the low 40s.
Ms. Whitmer, 48, has a history and easy rapport with Mr. Biden: He campaigned for her governor’s race in 2018 and she returned the favor, endorsing him before Michigan’s presidential primary and appearing with him at his last big rally in the state before the pandemic struck. She was one of the first to appear on Mr. Biden’s “Here’s the Deal” podcast and is a national co-chair for his campaign.
“They just seem to click,” Ms. Bayer said.
Still, many Michigan Democrats don’t want Ms. Whitmer to leave the state while she is still grappling with the outbreak, which has hit Michigan particularly hard, with more than 96,000 cases and 6,500 deaths as of Monday. And it has devastated the state economy, driving the unemployment rate to 14.8 percent, one of the highest in the country, as of June, the latest data available.
And while Michigan was among the first states to be severely affected by the virus, it has also had a recent uptick in cases, leading Ms. Whitmer last month to reinstate restrictions on public gatherings and some businesses, and to require all residents to wear masks indoors and in crowded outdoor spaces.
Those actions have spurred a backlash against the governor, included multiple recall campaigns — but it has also caused some of her supporters to question whether the state can afford to lose her at such a critical time.
“In talking to some of my friends who work in infectious disease, they think she’s done an incredible job, as do I,” said Julie Campbell-Bode, a Democratic activist from Royal Oak, a Detroit suburb. “Selfishly, we need her here. There is plenty of time for her to climb those mountains and I’m sure she will.”
Several observers also questioned how much she could help Mr. Biden win Michigan, a battleground state that Mr. Trump won by less than 11,000 votes over Hillary Clinton in 2016.
“Yes, she won the majority of the vote in Michigan, but she didn’t have coattails,” said Ed Sarpolus, founder of Target-Insyght, a polling and consulting firm based in Lansing. “Democrats didn’t take back the State House or Senate. He needs somebody who can win in the Upper Peninsula and northern Michigan, and she didn’t do all that well there.”
And there is widespread concern among Democrats about the line of succession if Ms. Whitmer leaves Michigan for Washington.
If Garlin Gilchrist, the lieutenant governor, were to take over from her, becoming Michigan’s first Black governor, he would be among the youngest governors in state history at 37. And he has little experience in governing: A former social media director for Barack Obama in 2008, he first ran for office in 2017, when he lost the race for city clerk in Detroit. The next year, Ms. Whitmer chose him as her running mate.
As lieutenant governor, Mr. Gilchrist serves in a largely ceremonial role, offering a tiebreaking vote if necessary. But he has had little chance to build a record of his own or demonstrate that he could hold onto the governorship in the 2022 election.
“Garlin Gilchrist has done reasonably well, but he hasn’t demonstrated that he can win,” Mr. Sarpolus said.