For Sen. Marco Rubio, multiple congressional investigations are not enough. The Florida Republican upped the ante on the IRS this afternoon, filing an amendment to an unrelated water resources bill to provide criminal penalties for similar acts in the future.

Rubio’s amendment would amend federal criminal law to provide for up to five years in prison for IRS employees found to engage in conduct that violates First Amendment protections of “political speech and political expression.”

Earlier in the day, Rubio had sent a letter to Treasury Secretary Jacob J. Lew demanding that acting IRS Commissioner Steven Miller resign from his post. The amendment and matching legislation are identical to a House bill unveiled Monday by Rep. Michael R. Turner, R-Ohio.

“Those responsible individuals should face all appropriate punishment available under current law, and all organizations and individuals who engage in political speech and expression should be protected against this kind of discriminatory behavior in the future,” Rubio said in a statement. “I commend Congressman Turner for championing this legislation in the House and hope our colleagues will join us in providing protections to deter this kind of governmental abuse from happening again.”

“Americans of all political beliefs have been rightly outraged by the revelation of the IRS’ efforts to target certain political organizations. The fact that this could occur with little to no corrective action against those who seek to silence their fellow citizens is unacceptable,” Turner said in a statement earlier Monday.

Rubio’s bid to amend the pending reauthorization of the Water Resources Development Act highlights a key difference between the House and the Senate. The Senate has no general germaneness requirement for amendments, so the IRS amendment could be allowed even on an unrelated water projects bill. (Of course, that assumes no one senator objects to moving to a vote on it.)

However, Rubio could be out of luck if the Senate moves to limit debate, or invoke cloture, on the water bill. If there’s no deal on amendments to the WRDA measure, that cloture vote would take place noon Tuesday.

Majority Leader Harry Reid, D-Nev., suggested the Senate will wait until the release of a report by the Treasury Inspector General for Tax Administration regarding the conduct of IRS officials in Cincinnati, Ohio. That report’s expected out this week.

“In the meantime, no one should jump to conclusions. But rest assured, as soon as we have the inspector general’s report, the Senate will quickly take appropriate action,” Reid said.

Emma Dumain contributed to this report.