Biden’s Calls for Unity Are Already Being Tested in Congress

Perhaps more than any recent president, Mr. Biden has staked his reputation and the fortunes of his administration on his ability to work with a polarized Congress where Democrats have only the slimmest margins of control. Despite the recent history of legislative inertia and toxic politics, Mr. Biden has made it clear that he believes he can leverage his 36 years of experience and relationships on Capitol Hill to work across the aisle and achieve the breakthroughs needed to get the nation through its multiple crises — this “rare and difficult hour,” as he put it.

He immediately set about trying to strengthen his bond with Republicans, inviting Senator Mitch McConnell of Kentucky, the Republican leader who waited a month to recognize him as president, and Representative Kevin McCarthy of California, the top House Republican who supported overturning his victory, to attend Mass with him Wednesday morning before the inauguration.

Mr. McConnell, in a lighter post-inaugural moment that served as a reminder of the clubby Washington circles in which the president has long been comfortable, claimed Mr. Biden and Vice President Kamala Harris as a “son and daughter” of the Senate because of their service there, while wryly pointing out that neither had ever been a member of the House, a chamber senators love to deride as the lowlier body. Ms. Harris received a bipartisan standing ovation in the Senate when she entered to preside for the first time after her swearing-in as vice president.

In his speech, Mr. Biden also reminded House and Senate members attending that he was one of them.

“Look, folks,” he said, employing one of his favorite expressions, “all my colleagues I served with in the House and the Senate up here — we all understand the world is watching, watching all of us today.”

But it is going to take more than Mr. Biden’s trademark backslapping and good nature to break through the persistent gridlock in Congress. Already, Republicans are mounting challenges to his cabinet nominees, and Mr. Biden nearly became the first president since at least Jimmy Carter to not win confirmation of a cabinet nominee during his first hours in office. At the last minute, Senator Tom Cotton, Republican of Arkansas, dropped his objection to the confirmation of Avril D. Haines to be the director of national intelligence. Still, nominees for other national security posts that are typically approved immediately after a president takes office remained stalled.