Sen. Al FrankenAl FrankenDems push for more action on power grid cybersecurity Congress poised to prohibit airlines from forcibly removing customers Sen. Franken spotted onstage at Grateful Dead concert MORE (D-Minn.) on Sunday called on supporters to reject one of President Obama's nominees to the Treasury Department.

Franken criticized nominee Antonio Weiss in no uncertain terms, arguing Obama had nominated the wrong person for the job of Treasury undersecretary for domestic finance. 

He argued Weiss would not put the middle class first and that he was too close to Wall Street.

"Join me in asking the President to withdraw Antonio Weiss’s nomination," Franken wrote in an email to supporters on Sunday, with a link to the petition. "We need a nominee who will put the middle class first."

Franken wrote that Weiss has worked on manuevers called "inversions," which are mergers that seek to lower a company's tax burden in the United States by moving its headquarters overseas.

"More than six years after the crash, the American economy is still recovering," Franken writes. "We got into that mess because we were willing to let Wall Street police itself. Foxes make poor guards of henhouses. We know that through bitter experience, and I’m not willing to let it happen again."

Franken is joining Sen. Elizabeth WarrenElizabeth WarrenLive coverage: Senate GOP unveils its ObamaCare repeal bill Overnight Regulation: Labor groups fear rollback of Obama worker protection rule | Trump regs czar advances in Senate | New FCC enforcement chief Budowsky: Dems madder than hell MORE (D-Mass.) and other liberals in opposing Weiss, setting up an internal Democratic Party fight with Obama. Weiss is an executive at the investment banking firm Lazard.

The White House has defended Weiss — and his values. 

"He is somebody who has spent some time thinking about some of the issues that the president believes are critically important," White House press secretary Josh Earnest said earlier this month. "For example, in 2012, Mr. Weiss co-authored a report called ['Reforming Our Tax System, Reducing Our Deficit']."

Earnest said Weiss's experience was an advantage. 

"This is somebody who has a very good knowledge of the way that the financial markets work," he said. "And that is critically important when you're asking somebody to take on a position in the federal government that has such a significant bearing on those markets."