Mr. Biden, a six-term veteran of the Senate, had trumpeted his deep Capitol Hill experience as one of his top selling points, telling voters that he was the singular man able to unite the fractious Congress and even come to terms with his old bargaining partner, Mitch McConnell, Republican of Kentucky and the minority leader.

But congressional Democrats, highly familiar with Mr. McConnell’s tactics, held no such illusions. Now, they worry that voters would punish them more harshly in the 2022 midterm elections for failing to take advantage of their power to enact sweeping policy changes than for failing to work with Republicans and strike bipartisan deals.

Congressional Democrats want far more than Republicans are willing to accept. Anticipating the Republican recalcitrance to come, Democrats are increasingly coalescing around the idea of weakening or destroying the filibuster to deny Republicans their best weapon for thwarting the Democratic agenda. Democrats believe their control of the House, Senate and White House entitles them to push for all they can get, not settle for less out of a sense of obligation to an outdated concept of bipartisanship that does not reflect the reality of today’s polarized politics.