One of the enduring storylines of Barack Obama’s presidency was the working relationship — and dare I say friendship — between Vice President Joe Biden and Senate Republican leader Mitch McConnell. The two personally negotiated deals on avoiding the economic perils of defaulting on the nation’s debts in 2011 and, two years later, falling off the fiscal cliff. “You’ve been a real friend, you’ve been a trusted partner, and it’s been an honor to serve with you,” McConnell said of Biden on the Senate floor in the final days of the Obama presidency in 2016. “We’re all going to miss you.” McConnell was back to talking about Biden on Capitol Hill on Wednesday. But this time his tone had changed. Big time. “How profoundly — profoundly — unpresidential,” McConnell said of the President’s speech on Tuesday expressing his support for a carve-out in the filibuster rules to allow voting rights measures to be passed by a simple majority. “I’ve known, liked and personally respected Joe Biden for many years. I did not recognize the man at the podium yesterday.” Which, well, harsh! But McConnell wasn’t done! He also said Biden’s speech was a “rant,” “incoherent,” “incorrect” and “pure, pure demagoguery.” Why was McConnell so mad? Well, at least part of that ire was playacting. McConnell wants to be as outraged as possible about the possibility of fiddling with the filibuster to send a signal to on-the-fence Democrats about what he believes the consequences would be of changing the rules. McConnell also could well be sending up a flare for former President Donald Trump, who has relentlessly attacked the Republican leader in recent months. See, I can attack Biden too! — and all that. But I don’t think politics alone explains just how vociferous McConnell was in his critique of Biden. It felt more personal — and my educated guess is that the Kentucky Republican thought of himself and Biden as two similar souls when it comes to the Senate. Sure, they disagreed on most issues when they served together, but they both found common cause on the sanctity of the filibuster. McConnell, in short, felt (and feels) betrayed by Biden. We can debate for days as to whether he should — particularly given the blockade McConnell and his Republican colleagues have constructed to stop much of the Biden agenda in the Senate. Whether or not McConnell’s anger is justified, however, is somewhat beside the point. It’s uniquely possible that the final two years of Biden’s first term will be under a Republican-controlled Senate, with McConnell as its leader. That can’t be an appetizing prospect for Biden — particularly after McConnell’s tirade against him Wednesday. The Point: Politics works on relationships. And the Biden-McConnell one seems very, very tense right about now.