President Trump's impeachment trial is set to wrap up without new witnesses being called.

Sen. Lisa Murkowski (R-Alaska) announced Friday she will vote against calling new witnesses, in a statement saying she "carefully considered the need for additional witnesses and documents" but ultimately decided against it.

"Given the partisan nature of this impeachment from the very beginning and throughout, I have come to the conclusion that there will be no fair trial in the Senate," she wrote. "I don't believe the continuation of this process will change anything. It is sad for me to admit that, as an institution, the Congress has failed."

Murkowski, who criticized the House of Representatives' "rushed and flawed" articles of impeachment charging Trump with abuse of power and obstruction of Congress, also appeared to criticize Sen. Elizabeth Warren (D-Mass.), writing that "some of my colleagues intend to further politicize this process, and drag the Supreme Court into the fray, while attacking the chief justice." Warren asked a question Thursday suggesting there had been a "loss of legitimacy of the chief justice."

As The Hill points out, Murkowski gives Republicans their 51st vote against calling new witnesses. Had Murkowski been a yes, this would have created a 50-50 tie, which NBC News writes "would have at least opened the door to the unlikely possibility that Chief Justice John Roberts could cast a tie-breaking vote." Sens. Susan Collins (R-Maine) and Mitt Romney (R-Utah) previously announced they would vote in favor of new witnesses, but no other Republicans have, with Sen. Lamar Alexander (R-Tenn.) on Thursday saying he'll vote no. Brendan Morrow