Where is Marco Rubio, and why?

Rich Lowry asks a question that has been on my mind: “Where the hell is Marco Rubio.” As I noted a week and a half ago, “for at least a week there have be reports that Rubio is ‘nearing’ and/or ‘edging towards’ a decision to endorse Cruz.” I added:

I don’t know what he’s waiting for. There isn’t much substantive difference between the two Senators and no one has made the anti-Trump case more forcefully than Rubio.

If Lindsey Graham can bite the bullet and back Cruz, Marco Rubio certainly should be able to. With early primary voting ongoing, the sooner the better.

Lowry quotes a New York Times article which offers a possible explanation for why Rubio hasn’t bitten the bullet:

Mr. Rubio, who praised Mr. Cruz as “the only conservative left in the race” after his exit, has been perhaps the most conspicuous holdout. He is one of the few Republican senators who gets along well with Mr. Cruz, and the two have been in touch since Mr. Rubio withdrew from the race.

But Mr. Rubio is likely to run again for president in 2020 should Republicans lose the White House this year, and, in making scores of thank-you calls to donors in recent days, he has been discouraged by some party financiers from supporting Mr. Cruz, according to a Republican strategist briefed on the calls.

Without Mr. Rubio’s imprimatur, many of his backers seem disinclined to back Mr. Cruz.

If Rubio actually is unwilling to back Cruz — and thereby try to save the Republican Party from a Donald Trump takeover — because some financial backers are discouraging him from doing so, this would mean that he is neither principled nor a leader. It should, as Lowry says, be remembered. Indeed, it should disqualify from the presidency.

If Rubio is withholding his endorsement for some other reason, I would like to know what that reason is.