Is Trump driving politicians out of the Republican party?

WASHINGTON — The longest-serving Republican in the Iowa Legislature became a Democrat this week. And in doing so, Representative Andy McKean made clear his move was all about President Trump. ‘‘If this is the new normal,’’ he said of Trump’s ‘‘unacceptable behavior,’’ ‘‘I want no part of it.’’

McKean’s move isn’t part of anything amounting to a Trump-inspired exodus from the GOP. Just as the size of the anti-Trump wing of the GOP electorate is often oversold, the number of Republican politicians leaving the party is an extremely rare exception to the Trump-supporting rule.

But there has been a Trump-inspired shift in the direction of party-switching in the United States. While for the better part of the last few decades, party-switching generally hurt Democrats and benefited the Republican Party — largely because of conservative Southern Democrats coming around to the GOP — these days, the movement is more leftward.

Ballotpedia has tracked party-switchers in state legislatures since 1994. Over that span, 71 state lawmakers have switched from Democrat to Republican, while 18 have switched from the GOP to the Democratic Party.

Only twice over that span have we had more Republicans switching to Democrat than Democrats switching to Republican in consecutive years: the tail-end of George W. Bush’s presidency (2006-07) and the last two years of Trump’s.

But that’s still only a handful of switchers. Where we’ve seen a bigger shift is in Republican lawmakers who leave the party but don’t join the Democrats. While Ballotpedia records only one in the period 1994 to 2015, since 2016, there have been 13. If you combine those who defected to the other party or for some other affiliation, 19 lawmakers have left the GOP since 2016, while 15 have left the Democrats.

Not all of those GOP defectors blame Trump, of course, but a review of their stated reasons shows many of them do cite Trump. Several of them were rising Republican stars in tough states. Others were long-serving members who decided to take a stand.

McKean’s colleague in the Iowa Legislature, now-former state Senator David Johnson, switched to independent during the 2016 election over Trump’s ‘‘racist remarks and judicial jihad,’’ calling Trump a ‘‘bigot’’ for suggesting the US-born judge overseeing the Trump University case, Gonzalo Curiel, was biased because of his Mexican heritage.

California state Assemblyman Brian Maienschein cited a number of reasons for his party switch three months ago, but he made clear Trump was one of them. ‘‘I don’t even know where to begin,’’ he said of Trump. ‘‘His conduct has been very offensive really since the beginning . . . his conduct was reprehensible, immature, counterproductive to what I believed was best for the country.’’

Maienschein shares one characteristic with many party-switchers: They left state parties rife with discord. Such is also the case in Kansas, where four state lawmakers left the GOP for the Democrats in 2018. While state politics and a divide in the state GOP played a role there, at least two of them — Senator Barbara Bollier and Representative Stephanie Clayton — also cited Trump.

‘‘I cannot be complicit in supporting that,’’ Bollier said of Trump. ‘‘I can’t call it leadership. I don’t even know what to call him. He is our president, but he is not representing my value system remotely.’’

Some of the youngest rising stars in the GOP have also departed over Trump.

In Connecticut, Aundre Bumgardner won a House seat at the age of 20 in 2014. Bumgardner, who is black, was hailed as ‘‘part of the next generation of leaders in our party’’ by the state GOP. But after losing in 2016, he announced last year that he had ditched the party over Trump’s response to the tragedy in Charlottesville, Va.

Similarly, Meagan Simonaire was elected as the youngest member of the Maryland House of Delegates in 2014, at just 24. She made national news last year for coming out as bisexual and decrying conversion therapy. Then, in October, she left the Republican Party, saying she couldn’t stay in a party that condones Trump’s ‘‘divisive rhetoric.’’

Hawaii state Representative Beth Fukumoto is another once-rising GOP star; she was featured on The Fix’s ‘‘40 under 40’’ list in 2014. She became minority leader of the state House before turning 30 and was tapped to help the national GOP recruit female candidates. Then in a February 2017 speech to the Women’s March in Honolulu, she spoke out against Trump’s comments about women and minorities, and the next month she announced her party switch.

These three and other party-switchers notably come from states where their now-former party wields little power, which undoubtedly weighed on some of their decisions. It’s also notable that many of them switched after losing or didn’t go on to seek reelection. That’s why McKean’s switch in Iowa is more notable; he was actually leaving the majority party and intends to seek reelection in 2020 as a Democrat.

Outside of state legislatures, a number of party-switching politicians have also cited Trump, including former US senator Gordon Humphrey of New Hampshire, former congressman Charles Djou of Hawaii, Honolulu City Councilor Kymberly Pyne, California Supreme Court Chief Justice Tani Cantil-Sakauye, and former Arizona attorney general Grant Woods (a former chief of staff to the late Senator John McCain).

Other Trump critics to leave the GOP include conservative columnist George Will; former congressman and current ‘‘Morning Joe’’ TV host Joe Scarborough; a longtime aide to three Republican administrations, Peter Wehner; and a well-known GOP strategist and top adviser to McCain’s 2008 presidential campaign, Steve Schmidt.