A lawmaker in the Iowa House of Representatives said he's leaving the Republican Party in part because of his disapproval of President Donald Trump.

Rep. Andy McKean, an Anamosa lawmaker, announced Tuesday that he plans to register as a Democrat and vote with the minority caucus.

"With the 2020 presidential election looming on the horizon, I feel, as a Republican, that I need to be able to support the standard bearer of our party," McKean said during a news conference at the Capitol. "Unfortunately, that's something I'm unable to do."

McKean said Trump is just one part of a bigger trend of partisanship in the country, which made him feel out of place in the Republican caucus. McKean said when he joined the Legislature 40 years ago, there were many moderates in the Republican Party. But now, according to him, the ranks have thinned.