As promised, here’s the video of Rick Santorum appearing on The Tonight Show last night, backing up the e-mailed endorsement of Mitt Romney he sent out to supporters late on Monday night. The erstwhile presidential candidate looked perfectly chipper and relaxed:

“Well, I met with Governor Romney last Friday, and you know, we’d been trying to work on a meeting, and I think we just needed some time. You know, it was a rough-and-tumble campaign. I can’t say it would’ve been an easy thing the next day to turn around and say, let’s just go forward. It was tough. … And, I felt comfortable after that meeting, and over the weekend I worked on it, and we decided to put it out late at night so it would be sort of the first thing people would see in the morning, and, you know… I laid out sort of the case, and just said, you know, here’s sort of what we went through, here’s the discussion, here’s why I decided… but this was a letter to my supporters, who were for me, to say, well here’s now why I think we should rally around Mitt Romney and support him.”

Santorum got a good bit of flak for the interpretably half-hearted missive; MSNBC’s Joe Scarborough, for example, called it a “bush league” endorsement, saying: “If you don’t want to endorse him, don’t endorse him. That’s fine. People will respect him for not endorsing him. Again, this is like Obama on gay marriage. Don’t try to have it both ways. Don’t endorse in the 13th paragraph. Be a man.” Harsh words, but this appearance gave Santorum a chance to address both the manner of his endorsement and his past criticisms (which we’ll likely see chop-shopped in Democrats’ ads) in a more easygoing setting, which I think he did successfully. In a nutshell: don’t read too much into my ‘thirteenth-paragraph’ endorsement, I was just laying out my case; campaigns are tough and emotional and I needed some time; I had a chance to talk out my reservations with Romney in our meeting, and I’m firmly on board.

So, that’s Romney’s most serious former rival declaring himself ready to let the campaign’s bygones be bygones and join Team NObama. Everybody in? Good. Let’s do this.