WATCH, READ: Sen. Romney's Speech On Why He Voted To Convict Trump On First Article

In an emotional speech before the U.S. Senate, Utah Sen. Mitt Romney, a Republican, announced he would vote to convict President Trump of impeachment on Article I, abuse of power.

"With my vote, I will tell my children and their children that I did my duty to the best of my ability," he said.

Romney, who served two terms as Massachusetts governor and won the 2012 Republican presidential nomination, was the only Republican to break with the party.

“I am profoundly religious. My faith is at the heart of who I am. I take an oath before God as enormously consequential," Romney said, as he clearly struggled to maintain composure. "I knew from the outset that being tasked with judging the president, the leader of my own party, would be the most difficult decision I have ever faced. I was not wrong.”

Ryan Williams was a spokesman in the Romney administration and worked on his 2008 and 2012 presidential campaigns. He said he believes Romney's vote comes down to following his conscience.

"Politically, this vote does not make any sense. He’s alienating members of his own party, he’s alienating the leader of his party, he’s angering the grassroots base," Williams told WBUR. "But I think this was a decision that wasn’t about policies it was about his personal believes, it was about his values and this was a personal decision."

"Thank you, Mr. President.

The Constitution is at the foundation of our republic's success and we each strive not to lose sight of our promise to defend it. The Constitution established the vehicle of impeachment that has occupied both houses of our Congress these many days. We have labored to faithfully execute our responsibilities to it. We have arrived at different judgments, but I hope we respect each other's good faith. The allegations made in the articles of impeachment are very serious. As a senator juror, I swore an oath before God to exercise impartial justice.

I am profoundly religious. My faith is at the heart of who I am. I take an oath before God as enormously consequential. I knew from the outset that being tasked with judging the president, the leader of my own party, would be the most difficult decision I have ever faced. I was not wrong.

The House managers presented evidence supporting their case and the White House counsel disputed that case. In addition, the president's team presented three defenses. First, that there could be no impeachment without a statutory crime. Second, that the Bidens' conduct justified the president's actions. And third, that the judgment of the president's actions should be left to the voters.

Let me first address those three defenses. The historic meaning of the words high crimes and misdemeanors, the writings of the founders and my own reasoned judgment convinced me that a president can indeed commit acts against the public trust that are so egregious that while they are not statutory crimes, they would demand removal from office. To maintain that the lack of a codified and comprehensive list of all the outrageous acts that a president might conceivably commit renders Congress powerless to remove such a president defies reason.

The president's counsel also notes that Vice President Biden appeared to have a conflict of interest when he undertook an effort to remove the Ukrainian prosecutor general. If he knew of the exorbitant compensation his son was receiving from a company actually under investigation, the vice president should have recused himself. While ignoring a conflict of interest is not a crime, it is surely very wrong. With regards to Hunter Biden, taking excessive advantage of his father's name is unsavory, but also not a crime. Given that in neither the case of the father nor the son was any evidence presented by the president's counsel that a crime had been committed, the president's insistence that they be investigated by the Ukrainians is hard to explain other than as a political pursuit. There's no question in my mind that were their names not Biden, the president would never have done what he did.

The defense argues that the Senate should leave the impeachment decision to the voters. While that logic is appealing to our democratic instincts. It is inconsistent with the Constitution's requirement that the Senate, not the voters, try the president. Hamilton explained that the founders’ decision to invest senators with his obligation rather than leave it to the voters was intended to minimize, to the extent possible, the partisan sentiments of the public at large.

So the verdict is ours to render under our Constitution. The people will judge us for how well and faithfully we fulfill our duty. The grave question the Constitution tasks senators to answer is whether the president committed an act so extreme and egregious that it rises to the level of a high crime and misdemeanor.

Yes, he did. The president asked a foreign government to investigate his political rival. The president withheld vital military funds from that government to press it to do so. The president delayed funds for an American ally at war with Russian invaders. The president's purpose was personal and political. Accordingly, the president is guilty of an appalling abuse of public trust.

What he did was not perfect. No, it was a flagrant assault on our electoral rights, our national security and our fundamental values. Corrupting an election to keep one's self in office is perhaps the most abusive and destructive violation of one's oath of office that I can imagine. In the last several weeks, I have received numerous calls and texts. Many demanded, in their words, that I stand with the team. I can assure you that that thought has been very much on my mind. You see, I support a great deal of what the president has done. I voted with him 80% of the time. But my promise before God to apply impartial justice required that I put my personal feelings and political biases aside. Were I to ignore the evidence that has been presented, and disregard what I believe my oath and the constitution demands of me, for the sake of a partisan end, it would, I fear, expose my character to history's rebuke and the censure of my own conscience.

I'm aware that there are people in my party and in my state who will strenuously disapprove of my decision, and in some quarters I will be vehemently denounced. I'm sure to hear abuse from the president and his supporters. Does anyone seriously believe that I would consent to these consequences other than from an inescapable conviction that my oath before God demanded of me? I sought to hear testimony from John Bolton, not only because I believed he could add context to the charges, but also because I hoped that what he might say could raise reasonable doubt and thus remove from me the awful obligation to vote for impeachment.

Like each member of this deliberative body, I love our country. I believe that our Constitution was inspired by providence. I'm convinced that freedom itself is dependent on the strength and vitality of our national character. As it is with each senator, my vote is an act of conviction. We've come to different conclusions, fellow senators, but I trust we've all followed the dictates of our conscience.

I acknowledge that my verdict will not remove the president from office. The results of this Senate court will in fact be appealed to a higher court. The judgment of the American people. Voters will make the final decision, just as the president's lawyers have implored. My vote will likely be in the minority in the Senate. But irrespective of these things, with my vote, I will tell my children and their children that I did my duty to the best of my ability, believing that my country expected it of me. I would only be one name among many, no more, no less, to future generations of Americans who look at the record of this trial. They will know merely that I was among the senators who determined that what the president did was wrong, grievously wrong. We are all footnotes at best in the annals of history. But in the most powerful nation on earth, the nation conceived in liberty and justice, that distinction is enough for any citizen.

Thank you, Mr. President. I yield the floor."