About a month ago, when Donald Trump was claiming that Ted Cruz probably was not eligible to be president, Trump was questioned by Jake Tapper about whether Marco Rubio was eligible.

Trump exhibited some legal understanding of the issue, citing an op-ed written by Harvard Professor Laurence Tribe. Trump’s conclusion was that he had no doubts Rubio was eligible:

“It’s a different [than Ted Cruz], very different thing because he was born here. He was born on the land.”

As the attacks on Cruz’s eligibility rose in intensity and Trump threatened suit, I predicted that Trump would have a hard time holding that line if Rubio rose in the polls and became Trump’s main challenger:

Will The Donald also sue to keep Marco Rubio off the ballot if Marco gains momentum again and runs attack ads? After all, many of the people who claim Cruz is ineligible also claim Rubio is ineligible because his parents were not citizens at the time of his birth in the United States. (Yes, I address that claim also in my prior post.)

I think Trump should sue. I’m not just saying that. I don’t know that Trump has standing, but he’s probably closer to it than most people out there. So go ahead, Donald, file the lawsuit, don’t just threaten it. And do it against Rubio too. I’m sick of hearing the threat. Just do it.

After the South Carolina primary, Rubio arguably is Trump’s main challenger.

And as I predicted, Trump didn’t hold the line on Rubio being eligible.

Today Trump was interviewed by George Stephanopoulous. When asked the same question Jake Tapper had asked a month ago, but now said he was not not familiar with Rubio’s situation, and had never looked at it. Despite having told Tapper he looked at it. And unlike his lack of prior concern, now he was not certain:

“I’m not sure, let people make their own determination … I don’t know. I’ve never looked at it, George, honestly, I’ve never looked at it.  Somebody said he’s not and I retweeted it.”

Nothing has changed in the Constitution. Only in the political landscape.

For my August 2013 analysis of why both Cruz and Rubio are eligible, regardless of where they stand in the polls, see natural born Citizens: Marco Rubio, Bobby Jindal, Ted Cruz