LANSING – Michigan Gov. Gretchen Whitmer on Thursday endorsed former Vice President Joe Biden for the Democratic presidential nomination, adding to Biden's momentum ahead of the Michigan primary next Tuesday.

"He's got my enthusiastic support and my vote on Tuesday," Whitmer said on the "Morning Joe" program on MSNBC.

Whitmer is also joining the Biden campaign as one of four national co-chairs, the Biden campaign announced.

Whitmer had repeatedly said she was unlikely to or had no plans to announce an endorsement ahead of the primary. But that changed after Biden's strong performance on Super Tuesday.

On "Morning Joe," Whitmer cited Biden's support for expanded health care under the Affordable Care Act and his support for the auto industry bailout during the Great Recession. She also said he is the best candidate to focus on "getting things done" and the "dinner table" issues she believes were key to her own election success in 2018.

On health care, Whitmer cited her own struggles dealing with health insurers when her late mother was ill with brain cancer 18 years ago.

"That's personal to me," and "I commiserated with Joe about that," she said, noting that Biden lost his son, Beau, to brain cancer.

Whitmer said 700,000 Michigan residents have obtained expanded Medicaid coverage under the Affordable Care Act signed into law under former President Barack Obama.

"When Michigan needed help ... Barack Obama and Joe Biden had our backs," she said.

Whitmer's earlier comments that she was unlikely to endorse before the primary were made when several Democrats were seen as having a realistic chance of winning the nomination. Super Tuesday recast the Democratic contest as a race between Biden and Vermont Independent Sen. Bernie Sanders. Respectively, they represent the moderate and more progressive wings of the party.

The Free Press reported Wednesday that Biden's strong performance Tuesday had stepped up pressure on Whitmer to endorse ahead of the Michigan primary.

More:Whitmer under pressure to make endorsement before Michigan primary, analysts say

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"A lot of things have changed," Whitmer said outside the Capitol on Wednesday, hinting at an announcement "in short order."

Asked Thursday whether Biden's strong performance on Super Tuesday influenced her decision to endorse, Whitmer said: "As a candidate who has been written off, I saw what happened with Joe Biden and their ability to pick themselves up off the mat, dust themselves off, and do what it takes to be successful."

Michael Joyce, a spokesman for the Republican National Committee, criticized Whitmer as "the perfect example of a tax and spend, big government Democrat." Her endorsement of Biden "proves once again there is no such thing as a moderate 2020 Democrat," Joyce said.

Whitmer, an attorney and former Senate minority leader from East Lansing, took office in January 2019 and has a growing national profile after delivering the Democratic response to President Donald Trump's State of the Union address in February.

Asked whether she is concerned about alienating supporters of Sanders with her endorsement, Whitmer told the Free Press she has "a great deal of respect for Sen. Sanders."

"This is a diverse party," she said. "What unites us is the fact that we are always working to expand health care access for Americans. That's what sets us apart."

Biden endorsed Whitmer during her 2018 gubernatorial bid and campaigned for her in Southfield. Sanders endorsed one of Whitmer's Democratic opponents, Dr. Abdul El-Sayed, in the primary, but supported Whitmer in the general election and rallied for her in Ann Arbor.

El-Sayed said Whitmer's endorsement "seems at odds with the challenges Michiganders face right now."

"Michiganders need good jobs that pay a living that aren't sent away in wayward trade deals," he said. "They need affordable housing, guaranteed health care, and protection for our Great Lakes. They need someone who’s going to rebuild our infrastructure. The only candidate running on that vision is Bernie Sanders."

Biden plans a Detroit visit on Monday. Sanders plans to visit Detroit on Friday and Grand Rapids on Sunday.

Contact Paul Egan: 517-372-8660 or pegan@freepress.com. Follow him on Twitter @paulegan4. Read more on Michigan politics and sign up for our elections newsletter.