It’s exceedingly rare for an elected official to abandon his or her political party, especially during a legislative session and an election year, which made this Des Moines Register story that much more noteworthy.

State Sen. David Johnson, one of the senior members of the Iowa Senate, says he has suspended his Republican Party membership to protest “the racist remarks and judicial jihad” by presumptive GOP presidential nominee Donald Trump. […] “I will not stand silent if the party of Lincoln and the end of slavery buckles under the racial bias of a bigot,” Johnson said, referring to Trump.

It’s worth noting that Johnson, a longtime state lawmaker who has always served as a Republican, did not partner with Democrats, but rather changed his voter registration to “no party.”

His decision does not alter control of the chamber in which he serves: Iowa’s state Senate already has a narrow Democratic majority, and Johnson’s break with the GOP leaves the Dems’ advantage unchanged.

It’s likely that Johnson has grown increasingly frustrated over time, because veteran lawmakers don’t usually walk away from their political party over a single offensive incident. One wonders, though, how many David Johnsons there are nationwide: Americans who’ve long considered themselves Republicans, who remember what the GOP was like before its radicalization, and who may be tempted to give up on the party in light of Trump’s nomination and antics.

In this case, Johnson also told the Des Moines Register he’s been disappointed by the GOP’s timidity in criticizing Trump – and to help prove the point, Iowa Gov. Terry Branstad (R) defended his party’s presidential nominee.

“Most people that know Donald Trump know that he’s not a racist and that he’s had tremendous relationships with minorities, and he has a lot of minorities and women that have been in key positions in his business,” Branstad told reporters on Monday.