At that point, would Obama be willing to expend enormous political capital by telling the country, as well Congress, that failure to accept the deal means a nuclear-armed Iran or war?

The other conceivable victory would be obtaining so-called fast-track negotiating authority for trade agreements, followed by the signing of the Trans-Pacific Partnership, which would be the biggest trade deal in U.S. history.

Obama’s problem is his own party. A majority of House Democrats oppose the pacts under consideration, and Senate Majority Leader Harry Reid has signaled little interest in bringing any agreements to a vote this year. The White House, already worried about the prospect of Republican control of the Senate in Obama’s final two years, has difficult calculations to weigh.

The president returns Tuesday from a trip to Asia, where his pivot policy had alienated China without assuaging U.S. allies. When he lands at Andrews Air Force Base, he may feel that even the recalcitrant and partisan Congress isn’t any messier than this uninviting global landscape.