What's driving this is the Democrats' recognition that they have a fundamental problem in the U.S. Senate that isn't going to change for a while. Even if you go back to the 2012 election, you'll see that Barack Obama only won 26 states in an effective landslide over Mitt Romney. In 2016, Hillary Clinton only won 20 states. And in the Senate, the Democrats only picked up two seats in an election cycle where the Republicans were defending 24 incumbent seats compared to only 10 for the Democrats.
What this means is that the Democrats will have a hard time maintaining a Senate majority over the long term, and can only hope to block the GOP through Senate maneuvers like the cloture vote and filibuster process. What Gillebrand fears most is that they'll make a stand on a Supreme Court nominee who isn't very meaningful (i.e., he's replacing Scalia and won't shift the balance of the court), and end up having the "nuclear option" deployed by the Republicans ... thereby turning the Democrats into an irrelevant minority for a long time.
“and end up having the “nuclear option” deployed by the Republicans ... thereby turning the Democrats into an irrelevant minority for a long time.”
It never ceases to amaze me that the GOPe does not want to make this move. If the roles were reversed, the RATs would (and already have) gone “nuclear!” The damned “repubicans” simply don’t want to have to lead.