Unlike John Kerry, frankly, it took John McCain a little longer to get over losing. Always kind of ornery, he tended to be a bit peevish.
What made McCain so appealing as a politician was the perception that he was above partisan politics. But running for President - winning the nomination, securing his party's support - is inherently partisan. And for the past five years, he's remained firmly in that partisan mindset.
Maybe it was watching Mitt Romney - a man he reputedly hates - lose to Obama, too, that made him come to peace with the existing power arrangement in DC. Or maybe he just got tired of the pettiness.
But it sounds like McCain led the charge to end the nuclear option from the GOP side.
A lot has been made of the structural reasons why "bipartisanship" (whatever that means in a given moment) has failed. Yes, gerrymandering. Yes, epistemic closure. Yes, a red state/blue state cultural divide.
But it has also simply been a GOP tactic. The deadlock in DC is a conscious choice of the GOP. It's policy as much as ideology.
Within a week, the immigration reform could pass the House. Within a month you could repeal the sequester with sensible cuts to spending and increased revenues spread out over a decade. Within a year you could address climate change.
I really believe the votes are there, if the GOP decided to let their members vote as they wished and as they thought was best for the country.
These would be compromises that would enrage both sides bases. Progressives would see entitlements cut. Conservatives would see... brown people get stuff. But stuff would get done.
For guys like McCain, who used to be "bipartisan", they can remember before the Tea Party scared the crap out of the GOP and enforced a rigid ideological purity. They remember the clubby Washington to horse trading and deal making.
And maybe this is the moment when the McConnell tactic of universal opposition ends and things get done.