Here we go … one more time.

First, the target was Barack Obama, the 44th president of the United States. He was born somewhere other than the United States, the allegation went.

Second, the target was Ted Cruz, junior senator from Texas, who actually was born in Canada to an American mother and a Cuban father.

Now it’s Marco Rubio, the junior senator from Florida, who was born in the Sunshine State, but whose parents immigrated there from Cuba.

All three men allegedly are constitutionally ineligible to run or serve as president.

The man making the assertion? Donald J. Trump, the frontrunner for the GOP presidential nomination.

Trump now says Rubio might not be eligible. His parents’ aren’t American, Trump said. Oh, wait. Rubio was born on U.S. soil. U.S. law says he’s a citizen automatically. Doesn’t matter, Trump asserts. He questions the eligibility, just as he has done with Cruz, even though U.S. law granted young Ted citizenship because Mama Cruz is an American citizen.

And the president? Well, he was born in Hawaii. Trump hasn’t stopped questioning his eligibility, either, even though the president’s late mother also was a U.S. citizen.

Trump is relying on others’ assertions. He’s using social media to send out the doubts that he denies planting. Sure thing. He’s adding plenty of irrigation to the doubts, though, by continuing to provoke needless discussion and unfounded questions about one of his opponents.

Will this latest specious assertion do any damage to Trump? I’ve noted before that I am done predicting such things. This campaign has entered a parallel universe where the normal rules of decency and decorum no longer apply.