Robert Kuttner of The American Prospect explains the dilemma of divided government:

Can Biden Govern With a Republican Senate?
It now looks like Biden will squeak through by taking Michigan, Pennsylvania, and Wisconsin. But in the Senate, Republicans will likely have 51 seats.

If Mitch McConnell is leader of a Republican majority again, what then? For starters, Biden will have to govern as a more centrist president. It will take some doing for him to get a Cabinet confirmed.

The most important players will be the three Republican Senate moderates: Lisa Murkowski of Alaska, Mitt Romney of Utah, and Susan Collins of Maine. Biden will need to reach out to them and see if they will occasionally break Republican caucus discipline and vote to pass crucial legislation and confirm nominees.

Something similar occurred in 2009 when President Obama found three Republican senators to help him pass the Recovery Act—Arlen Specter (Pennsylvania), Olympia Snowe (Maine), and, yes, Susan Collins. Their price was a much weaker act that redirected hundreds of billions from public investment to tax cuts.

Thus the danger. To get nominees confirmed, Biden would need to shop them first to McConnell and then to the three moderates. That means his Cabinet will be even more centrist than it already was going to be. And forget Rooseveltian legislation in the first two years.

One ray of hope: There is a very vulnerable class of GOP senators up in 2022. But in the meantime, Biden has to deliver something to an anxious electorate.