WASHINGTON — President Trump and Congress face a mountain of unfinished business — and chances are that most of it will stay unfinished.

Of course, no one knows what will happen, and the president and congressional leaders of both parties have made the usual noises about cooperation. “There are a lot of good things that we can do together,” the president said at a press conference today.

You should take these pledges with a healthy dose of skepticism.

Here’s a partial list of areas where Congress and the president might act: health care (Medicare, Medicaid, the Affordable Care Act, drug prices); immigration; taxes; huge budget deficits; infrastructure; adequate defense spending; and the minimum wage, to name just a few.

Some compromises can be imagined: Democrats might support Trump’s “wall” on the southern border in return for Republicans backing permanent legal status for so-called DACA immigrants — children who were brought to the United States by parents or others when they were young. (DACA stands for “Deferred Action for Childhood Arrivals.” There are about 690,000 active DACA recipients.)

But the president had two years and control of both houses of Congress to arrange such a compromise. With Democrats having won the House, are the chances of achieving it now so much better? It seems doubtful. The level of mistrust is enormous.

Consider some other obstacles to cooperation.

First, there are the normal differences of ideology and political philosophy, which have grown as Congress and public opinion have become more polarized. Next, there’s the hostile fallout from aggressive congressional investigations of the Trump administration, as well as the Mueller investigation; these are inevitable and bound to stoke ill-will. Finally, there’s a feeling in both parties that inaction is often more politically advantageous than compromise. It’s better to have an “issue” than a messy negotiation.

What might make political sense for both congressional Democrats and the president is to advance competing political agendas, not with the intent of changing policies, but with the purpose of building support for the 2020 presidential election.

Trump would concentrate on foreign affairs (where he has more independent power to act) and the economy. Meanwhile, congressional Democrats would emphasize their efforts to fortify the “safety net” and improve the economic lot of the middle class. The House would pass legislation embodying these goals, which would either die in the Senate or be vetoed by the president.

It’s a plausible political strategy for both parties with one important caveat: What’s good for the politicians may not be good for the country.

Robert Samuelson is a columnist with The Washington Post.

Robert Samuelson