Coming soon: The death of the filibuster

The filibuster is in peril.

With Republicans expected to change the Senate rules to slash debate time on President Donald Trump’s nominees this week, it will mark the third time the “nuclear option” — changing Senate rules by a simple majority — has been triggered in just six years.

Each of those unilateral moves by a Senate majority to weaken the Senate’s age-old precedents centered on nominations, leaving the legislative filibuster and its 60-vote threshold unscathed. But some senators say it’s just a matter of time before even that Senate...