Legislation comes amid claims Trump could use authority to excuse self from potential wrongdoing

Congressman Al Green on Thursday is leading a trio of lawmakers in introducing a constitutional amendment to prevent presidents from using their pardon power to excuse themselves from wrongdoing they commit while in office.

"To do so would lawfully allow the president to commit the most egregious acts with impunity," Green said in a statement. "However, because someday some unprincipled President might attempt a self-pardon, we are filing a constitutional amendment to make clear what people of good will believe true."

Congressmen Seth Moulton and Brad Sherman joined Green in introducing the bill.

Neither the legislation nor Green's announcement mentions President Donald Trump by name, but questions have mounted about the president potentially pardoning himself or his top staff amid investigations into his campaign's alleged ties to Russian attempts to influence last year's presidential election.

Trump's recently-appointed communication director Anthony Scaramucci acknowledged the president has discussed pardon issues in the Oval Office, but called claims the Trump is planning to pardon himself "nonsense".

Trump recently tweeted presidents have "the complete power to pardon".

In order to pass on Capitol Hill, the proposed amendment will require a two-thirds majority in each chamber, which would likely be a tough task for the three Democrat congressmen as Republicans firmly control the House, and narrowly hold the Senate.

It would then have to be ratified by at least three-fourths of U.S. states.

The legislation is expected to hit the federal register Friday, Green's office said.

House lawmakers leave for a month-long summer recess that day, meaning any action on the bill would likely be forestalled until they return.