President Trump has suggested the filibuster should be eliminated to help move along his legislative agenda, though you might not know that's what he was talking about when he tweeted this on Tuesday:
The filibuster used to be a rare and powerful tool for lawmakers to use when they wanted to hold up the normal course of business. But as rules changed to require fewer votes to shut one down, senators began to invoke it as a regular threat. Now, there are even fewer circumstances where it can be used.
These two episodes of Ron's Office Hours look at what the filibuster is, how it's changed and what it might mean for Trump's agenda.
In Part 1, NPR senior editor and correspondent Ron Elving looks at the history.
Part 2 covers what may lay ahead, for the filibuster and for Trump.