Why endorse someone who’s probably still 12-18 months from formerly announcing her candidacy? Because: McCaskill, famously, was one of the first prominent Democrats to back The One over HIllary six years ago. She helped make him a credible challenger at a moment when Team Clinton was trying to frame him as not yet ready for primetime. She also said this of Bill Clinton on “Meet the Press”: “I think he’s been a great leader but I don’t want my daughter near him.” In other words, McCaskill’s very, very much on the outs with a notoriously ruthless political operation that stands a real chance of capturing the White House three years from now. If she doesn’t do something dramatic to fix that, she’ll end up as one of the least influential Democrats in Congress.

So she’s doing something dramatic. Time to kiss the ring:

“Hillary Clinton had to give up her political operation while she was making us proud, representing us around the world as an incredible Secretary of State, and that’s why Ready for Hillary is so critical,” McCaskill said. “It’s important that we start early, building a grassroots army from the ground up, and effectively using the tools of the Internet – all things that President Obama did so successfully – so that if Hillary does decide to run, we’ll be ready to help her win.”

Sen. McCaskill commended Ready for Hillary for embracing the early supporters of then-Sen. Obama, saying, “They aren’t only reaching out to folks who supported Hillary in 2008. They’re helping to show that regardless of who you supported for President back then, we can all agree today that there is nobody better equipped to be our next President than Hillary Clinton.”

The fact that she’s willing to shank Joe Biden and other would-be Democratic contenders this early in the game tells you either (a) that she feels, probably rightly, that she has far more to fear from the Clintons than from any of their competitors or (b) that Beltway Democrats think Hillary’s basically a lock to run and win the nomination. Chris Cillizza makes a good point too about McCaskill’s self-interest in all this:

McCaskill knows that her political future in Missouri is a difficult one. She almost certainly would not be in the Senate right now if Republicans hadn’t nominated Todd “legitimate rape” Akin in 2014. Missouri has moved from a swing state to a GOP-leaning one in the last decade and there’s no reason to believe, demographically speaking, that it will move back toward Democrats any time soon.

That means that McCaskill will face a VERY difficult race in 2018. She knows that and may well be looking at her other political options — one of which would be to serve in a Clinton Cabinet. The best way to set yourself up for that possibility is to pick a candidate as early as possible — see Tim Kaine’s endorsement of Obama in 2007 — and then work like hell to try to get them elected.

Right, although I wonder if even sustained pro-Hillary cheerleading would be enough to earn McCaskill a spot in the cabinet after the betrayal of 2007. More likely, I think, is that she’s hoping President Hillary will come to Missouri and stump for her in 2018 in order to turn out Democrats. Unless the GOP pulls the pin on another Akin-esque grenade in the primaries, they’ll have a great chance to win that seat. A big Democratic showing will be McCaskill’s only chance and the Clintons (and her old friend Barack) are the way to make that happen.

Exit question: Which other Democratic Hillary enemies should we expect to do some early ass-kissing in order to make nice?

Visit NBCNews.com for breaking news, world news, and news about the economy