SALT LAKE CITY (AP) — Mitt Romney hasn't yet decided whether President Donald Trump should be impeached, but the Republican senator from Utah on Thursday stuck by criticism that has earned him a stream of insults from Trump on Twitter.

Romney said that while he thinks some things the president has done are wrong, it doesn't necessarily mean Trump should be removed from office.

"I will keep an open mind until and unless there is some kind of decision reached by the House, and then I will evaluate that information at that point," he said, referring to the House impeachment inquiry. "It's a purposeful effort on my part to stay unbiased and see the evidence as it's brought forward."

Romney's comments came following an appearance at a Salt Lake City event about the increasing number of people sickened by a mysterious illness associated with vaping.

Trump's Saturday Twitter stream came after the senator became one of the few in the GOP to speak out against Trump's call for China to investigate the family of presidential hopeful Joe Biden.

Romney calmly brushed off the president's rebuke, saying he doesn't follow him on Twitter.

Romney repeated his criticism of Trump's apparent overtures to China and Ukraine, as well as the more widely shared disagreement with Trump's decision to pull U.S. troops from Syria's border. Romney also said he agrees with Trump on other policy positions and expects him to win the GOP nomination and another term.

"Whether you support the president or not I think he's by far the most likely to get re-elected," as many Democratic candidates take increasingly further left positions, Romney said. He declined to comment on how possible impeachment might affect the 2020 race.

Romney, a former governor of Massachusetts, said he couldn't imagine running again for president himself. He also said he hasn't spoken with his GOP Senate colleagues about the impeachment process.

Under the Constitution, the U.S. House votes on whether to impeach, and the Senate decides whether a president should be removed from office.