"The first possibility is that the showdown over abolishing the filibuster rule takes place now. If so, its framing will be Democrats’ general anger at Mr. Trump as well as their specific outrage over what they consider the theft of a Supreme Court seat by Republicans’ refusal to give a hearing last year to President Barack Obama’s nominee, Judge Merrick B. Garland, to fill the vacancy created by Justice Antonin Scalia’s death in February 2016. "The substantive stakes now are relatively low: Judge Gorsuch appears to be very conservative, but so was Justice Scalia. Confirming Judge Gorsuch would merely preserve the ideological status quo on the closely divided Supreme Court. Should the confirmation move ahead, all 52 Republican senators will probably stick together, bolstered by a few Democrats from conservative-leaning states. Those are enough votes to easily clear the way for confirming Judge Gorsuch — and all future nominees — by a simple majority. "But the dynamics could play out differently in a second situation: Judge Gorsuch is confirmed, but the filibuster rule survives. If Mr. Trump then gets to nominate a successor to a moderate or liberal justice, the substantive stakes would be much higher." . . .