Sen. Mike Lee said Wednesday that Donald Trump "scares me to death" and that he still has concerns about the presumptive Republican presidential nominee and isn't ready to endorse him.

The Utah Republican, who previously backed Texas Sen. Ted Cruz for president, also told constituents during an evening tele-town hall that he finds likely Democratic nominee Hillary Clinton unacceptable, suggesting that he might be able to endorse Trump down the line. But as for now, Lee is withholding his support from the New York businessman.

"I have not supported Donald Trump up to this point, I have not endorsed him," Lee said. "I have some concerns with him. He scares me to death; so does Hillary Clinton. There is no easy choice right now.

"I'm going to continue to watch this" the senator added. "I'll make the decision as best I can, but I'm not there yet."

Lee, a Tea Party conservative, was first elected in 2010 after defeating a sitting Republican in a primary. His small government, constitutional approach to governing, is at odds with Trump, a populist who envisions a larger role for the federal government than most conservatives in his party.

Lee is among many congressional Republicans who have either held off on endorsing Trump (House Speaker Paul Ryan of Wisconsin is another), said they will never endorse him, or said they would vote for him but claimed that their vote did not constitute an endorsement.

Lee, asked by a constituent from Utah who called in to ask whether he could support Trump, joked that he asked a friend in London if England would still want America back with Trump as president, and that his friend said: "It looks like Donald Trump wants to make America Great Britain again," an apparent reference to the country's monarchy.

Some Republicans have taken issue with what they interpret to be Trump's view of the presidency as one that possesses expansive executive powers. In one of the GOP debates, Trump insisted that his military commanders would follow his orders, even if his orders were unlawful. Trump later issued a retraction, saying he would never order his military commanders to conduct illegal actions.