Jones, who faces a tough reelection this year, made his announcement hours before the Senate voted to acquit Trump.

“Senators are elected to make tough choices. We are required to study the facts of each issue before us and exercise our independent judgment in keeping with the oaths we take. The gravity of this moment, the seriousness of the charges, and the implications for future presidencies and Congresses all contributed to the difficulty with which I have arrived at my decision," Jones said in a statement.

In a speech on the Senate floor, Jones said he was concerned about the precedent set by the Senate not calling witnesses, such as former national security adviser John Bolton, in the trial. But he also said there was still sufficient evidence for convicting Trump, and that evidence "clearly proves" that Trump used his office to seek to coerce a foreign government to interfere in the election.

"His actions were more than simply inappropriate. They were an abuse of power," Jones said. He added that he had more pause about the charge of obstruction of Congress, but said the evidence in the trial ultimately proved the case.

Sinema, in a statement, said "the facts are clear" and "while White House attorneys claim this behavior is not serious, it is dangerous to the fundamental principles of American democracy to use the power of the federal government for personal or political gain."

Manchin didn't reveal his position until 10 minutes before the scheduled vote. The West Virginia Democrat delivered a floor speech earlier this week, but said he remained undecided. During that speech, he suggested that the Senate censure the president.

In his statement announcing his position, Manchin said he came to his conclusion "reluctantly" but that the House managers proved their case against the president.

"I must vote yes on the articles of impeachment," the West Virginia Democrat said. "I take no pleasure in these votes, and am saddened this is the legacy we leave our children and grandchildren."