The U.S. Senate candidacy of Richard Painter is more notable for what it says about the Republican Party than for what it tells us about the DFL, the party whose nomination Painter seeks.

Painter’s credentials as a Democrat are slender, to say the least. The University of Minnesota law professor, a self-described “centrist,” has identified himself for some 30 years as a Republican, and he served in the George W. Bush administration as the White House ethics lawyer.

But when the prominent “NeverTrump” spokesman decided to seek office himself, it wasn’t as a Republican, but as a Democrat.

To be sure, Painter has adopted positions that fit well with the DFL, or at least with the metro-area liberal wing of the party: he favors universal health care, opposes copper-nickel mining and advocates campaign finance reform.

But his rationale for running is his opposition to President Donald Trump, and to that end he promises not to attack his DFL rival, appointed U.S. Sen. Tina Smith.

Painter’s party switch is indicative of Trump’s takeover of the Republican Party. The senators Trump vanquished in the GOP nomination battle in 2016 — Marco Rubio, Ted Cruz, Lindsey Graham — have all fallen in line despite having previously denounced him as dangerously unqualified. Jeff Flake and Bob Corker, two mainstream conservative senators who object to Trump’s bombastic style and at least some of his policies (notably immigration) opted against seeking re-election.

The Republican establishment — the advocates of free trade, muscular foreign policy alliances and deficit reduction — has surrendered. The more centrist faction of the Republican caucus in the House is retiring in droves. Members of the “NeverTrump” faction of the Republicans may be vocal, but they aren’t running for office, not as Republicans.

The immediate future of the Grand Old Party has, for better or worse, been ceded to Trump. And the longer the party goes without a credible internal challenge to his nationalist themes, the longer it will take for it to find its way back to what it was.