Whitmer said Biden's son, former Delaware Attorney General Beau Biden, perished in 2015 from "the same brain tumor that took my mom's life," and she praised his efforts in the Obama administration to widen access to health care through the passage of the Affordable Care Act, which allowed her to expand Medicaid coverage in Michigan.

Whitmer also sought to tie Biden to former President Barack Obama's bailout of major U.S. car manufacturers in 2009 following the Great Recession, remarking that the federal intervention "was a great thing for our economy as a nation, but it was personal to us here in Michigan."

Michigan has wielded an outsized influence in American electoral politics since the 2016 presidential race, when Donald Trump's narrow, upset victory there over Hillary Clinton — as well as his similarly unexpected wins in Pennsylvania and Wisconsin — propelled him to the White House.

"I think we all know Michigan is incredibly important," Whitmer said Wednesday. "All roads to the White House lead through my state and I want to make sure that we've got a strong ability to help impact where we are headed as a nation."

Although Vermont Sen. Bernie Sanders, Biden's chief rival for the 2020 Democratic nomination, triumphed over Clinton in Michigan during the party's 2016 nominating contest, a Detroit News/WDIV-TV poll released Tuesday shows Biden ahead of Sanders by nearly 7 percentage points in the state.

Sanders has repeatedly needled Biden over his support for trade deals including the North American Free Trade Agreement, arguing that Trump would "decimate him on that issue" in the industrial states Democrats need to clinch in November.

Biden dismissed that prediction in an interview Thursday with NBC's "Today" and projected confidence ahead of Michigan's primary, which could prove to be a decisive contest between the two frontrunners.

"Now, let's go to Michigan, Bernie, and let's see if that's true," he said. "I'm the guy that helped bail out the automobile industry. What'd you do, old buddy?"