Indeed, Jeff Kaufmann, the chairman of the Republican Party of Iowa, criticized Mr. McKean, saying that he had made “a commitment to the voters” of his district, who had elected him as a Republican, and that by changing parties, he had violated their trust.
“It’s disappointing that he felt the need to deceive Iowans,” Mr. Kaufmann wrote on Twitter. “If the people of District 58 can’t trust him on something as simple and fundamental as what party he belongs to, how can they trust him on any issue.”
The Democratic Legislative Campaign Committee, which works to elect Democrats to state legislatures, praised the move. Its executive director, Jessica Post, called Mr. McKean “courageous” and noted that Democrats are now four seats away from taking control of the Iowa House.
Mr. McKean emphasized that his choice was difficult, but he said that when he returned to Des Moines in 2017, after his long hiatus, he “found a very different place,” that was “more partisan and regimented.”
The Republican caucus had changed significantly, he added, and he felt increasingly uncomfortable within it.
Still, Mr. McKean apologized to his Republican colleagues for not having been “a better team player.”
“I might have limped along, attempting to work within my caucus for what I felt was in the best interest of the people I represent, if it hadn’t been for another factor,” he said.
“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. Unfortunately, that is something I’m unable to do.”