Whitmer announced her support Thursday on MSNBC’s Morning Joe. Biden is expected to campaign Monday in Detroit; it would not be a surprise to see Whitmer by his side there.
"I think that the blueprint from 2018 about showing up, focusing on the dinner table issues, and getting things done is exactly what Joe Biden represents," said Whitmer, referencing the 2018 Democratic wave that helped sweep her into office, "and that's why he's got my enthusiastic support and my vote on Tuesday."
Whitmer tweeted after her announcement that she would also be joining the campaign as a cochair. She joins Delaware Rep. Lisa Blunt Rochester, Louisiana Rep. Cedric Richmond, and Los Angeles Mayor Eric Garcetti in that role.
The endorsement could be a boost for the former vice president in his battle with Sen. Bernie Sanders, who beat Hillary Clinton in Michigan’s primary four years ago. (Sanders endorsed Abdul El-Sayed, a Whitmer rival two years ago.)
Michigan’s primary next week will test the coalition Biden has built in the last few days by running up the score with black voters in the South while also winning in the Midwest (Minnesota), Northeast (Massachusetts), and Texas. Whitmer had been under increasing pressure to pick sides, the Detroit Free Press reported Wednesday. A Detroit News/WDIV-TV poll this week found Biden leading Sanders in the state by about 7%.
"You all know that politics can change fast," Whitmer said on MSNBC. "A few days can be a lifetime. What we've seen in terms of the ability to coalesce and build a coalition that really has diverse representation — that is reflective of who we are as a party and what we need as a nation — has really started to show that Joe Biden is our strongest candidate going into the fall. I believe that. And I am excited about his candidacy."
Biden campaigned for Whitmer during her 2018 race, which she won convincingly.
Whitmer, 48, has been the subject of vice presidential speculation given her youth, gender, and success in a battleground state. When Detroit hosted the second Democratic presidential debate last summer, she had a featured role as host. And she acknowledged then that candidates were sounding her out and courting her for an endorsement.
“I think everyone knows that the path to the White House goes through Michigan and a handful of other states,” Whitmer told BuzzFeed News in an interview at the time.
“I really do want to see these candidates show up,” Whitmer added. “I want to see the work that they do — how they react under pressure and what, really, they’re going to be able to do on behalf of the people of Michigan.”
On Wednesday she signaled she'll be a visible part of Biden's team.
"I am eager to take part in a lot of the national conversation around his campaign because I think we all know Michigan's incredibly important," she said on Morning Joe. "All roads to the White House lead through my state."
Biden has been sweeping up endorsements since his success on Super Tuesday, pulling in support both from backers of former candidates who are now endorsing him and from politicians who have stayed out of the race until now.
Michigan’s last Democratic governor, Jennifer Granholm, endorsed Biden on Wednesday.