"It is very clear that Donald Trump is a better choice than Hillary Clinton," Stewart said. "At the end of the day I will be voting for Donald Trump."
However, earlier this month after a video was released of Trump talking about kissing and groping women without consent, Stewart had issued a statement calling for him to resign.
It said, "Unlike the Democrats who have proven completely unwilling to hold Secretary Clinton accountable for her illegal activities that endangered our national security, I am willing to hold Mr. Trump accountable. I am therefore calling for him to step aside and to allow Mike Pence to lead our party."
Stewart explained his decision to vote for him anyway now saying, "At that time I was so disappointed in Trump that I did ask him to step down and I did think Mike Pence should be our leader. But that didn't happen. Mr. Trump is still our nominee."
He said voting for anyone but Trump — such as independent Evan McMullin, who is statistically tied in polls in Utah with Clinton and Trump — is simply a vote for Clinton.
"At the end of the day, our choice is Hillary Clinton or Donald Trump," Stewart said.
"These other candidates are just not going to win," he said. "Given that choice, it's very clear to me what is better for our country. It is very clear that Donald Trump is a better choice than Hillary Clinton."
He added, "In a practical way, if you vote for a third party candidate, you truly are giving a vote to Hillary Clinton because you are not giving her opponent that vote that he needs to beat her."
Stewart's Democratic opponent, Charlene Albarran, blasted Stewart for what she said was flip-flopping.
"Last summer, Chris Stewart called Donald Trump our modern-day Mussolini, then three weeks later he endorsed him, following Chaffetz. Then last month, he denounced him again, clearly stating he will not vote for Trump, following Chaffetz again. Yesterday, he declared he will be voting for Trump, following Chaffetz one more time."
Albarran said, "We need a leader, not a follower. We need a representative who knows what they are doing and [who will] stand up for what they believe. I will lead. I stand firm on my beliefs."
Both Stewart and Chaffetz have large leads in the polls and are expected to win easily.
They join Sen. Orrin Hatch, U.S. Rep. Rob Bishop and state House Speaker Greg Hughes in pledging to vote for Trump. Utah Gov. Gary Herbert, Sen. Mike Lee and Rep. Mia Love have said they will not vote for Trump, but they have not said who will get their votes.