Hundreds of lawyers have signed onto an open letter criticizing Senate Majority Leader Mitch McConnell for his comments saying the Senate's upcoming impeachment trial does not have to be impartial.

In the letter to the Senate, published Tuesday by the group Lawyers Defending American Democracy, the lawyers said that McConnell's "assertions cannot withstand scrutiny."

"Just because the Constitution commits the impeachment process to a 'political' branch of government and senators may legitimately promote their partisan self-interest as part of the legislative process, does not mean they are permitted to do so when serving as judges and jurors in an impeachment trial," the letter reads. "To the contrary, as the adjudicators of impeachment, they have a duty to serve in a quasi-judicial capacity."