And perhaps most importantly, Biden and McConnell have a real relationship — forged over the years as Senate colleagues and combatants. McConnell was the only Senate Republican to attend the funeral for Biden’s son Beau in 2015, and he’s largely stayed away from GOP attacks on Biden’s other son, Hunter.

“They have negotiated big things before. They’ve come through some very hard and even bitter fights over judicial confirmations,” Sen. Chris Coons (D-Del.), a close Biden ally, said in an interview. “But I think they’ve managed to stay friends or have a working, professional relationship even in the hardest of times.”…

Some Republicans still grouse about the delays that Democrats put on Trump’s nominees, raising the prospect of a protracted fight right out of the gate for Biden as he staffs up amid a pandemic and economic crisis. GOP senators looking at a presidential run in 2024 will have further political incentive to gum up the works in a bid for the spotlight.

“Mitch McConnell will force Joe Biden to negotiate every single Cabinet secretary, every single district court judge, every single U.S. attorney with him,” said Sen. Chris Murphy (D-Conn.). “My guess is we’ll have a constitutional crisis pretty immediately.”