Story highlights The musician says he plans to run for Senate in Michigan

Sens. Warren and Schumer have seized on the star's supposed campaign bid

(CNN) Musician Kid Rock is insisting his tweet about running for the Senate is no joke, and at least two high-profile Senate Democrats are taking him at his word.

"I know a lot of people are thinking: this is some sort of joke, right?" Massachusetts Sen. Elizabeth Warren wrote in an email to supporters obtained by CNN and first reported by the Boston Herald.

"Well, maybe this is all a joke — but we all thought Donald Trump was joking when he rode down the escalator at Trump Tower and announced his campaign, too," she said.

"And sure, maybe this is just a marketing gimmick for a new album or tour — but we all thought Donald Trump was just promoting his reality TV show, too," she added.

The email links to a fundraising page for Michigan Democrat Sen. Debbie Stabenow -- Kid Rock's would-be opponent -- and Warren's reelection campaign.

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