08/08/2012 12:35 pm ET Updated Aug 08, 2012

Ron Johnson: Harry Reid Owes Senate An Apology For His Claim About Mitt Romney's Taxes

Mitt Romney wants Senate Majority Leader Harry Reid (D-Nev.) to "put up or shut up" on his claim that the presumptive GOP nominee paid no taxes for a decade. Sen. Ron Johnson (R-Wis.) joined in the criticism on Tuesday, saying he thinks Reid should also apologize for his conduct not only to Romney, but to the entire Senate.

"It's totally inappropriate for the Majority Leader to take to the floor of the Senate and basically be a flack for President Obama," Johnson told reporters in Wisconsin after a luncheon event sponsored by WisPolitics.com. "You should not be running a campaign from the floor of the Senate."

"I think Senator Harry Reid really owes Governor Romney an apology," he added. "I think he owes the Senate an apology."

In a recent interview with The Huffington Post, Reid said an anonymous Bain Capital investor told him that Romney paid no taxes for a decade.

"He didn't pay taxes for 10 years! Now, do I know that that's true? Well, I'm not certain," Reid said in the interview. "But obviously he can't release those tax returns. How would it look?"

Reid later reiterated his claim on the floor of the Senate.

Romney has vigorously denied the allegations and demanded to know where they came from. He has also continued to refuse to release more of his tax returns, which could definitively refute Reid's charge.