Just remember, it was the Dems who came up with the nuclear option, aka “The Reid Option” (after Harry Reid). We warned them that it was a bad decision at the time. They wouldn’t be in power forever. And now they opened Pandora’s Box.
Per the Constitution, the Senate, like the House, sets its own rules for debating proposals. At one time, the Senate allowed for “unlimited debate”, in which a person could talk and talk and talk (the original “filibuster”) to prevent voting on a proposal–and tying up the Senate from considering any other business. A few decades back, the Senate changed its rules to prevent such blockading, requiring at least 60 members to agree to vote on something. If they didn’t agree, then the proposal was taken off the table and the Senate could proceed to other business. The inability to achieve 60 members “voting for cloture” (i.e., to stop debate) then became called a filibuster.
When the Democrats recently had a majority in the Senate, they changed this rule so that, for non-SCOTUS judge nomination, a majority of the Senate could close debate and proceed to voting. This was because the Republicans were refusing to accept some of the judges that Obama had nominated. Changing the rules requires only a majority vote, and is not debated. This change in rules–allowing a vote without needing the 60 votes for cloture–is what is called the “nuclear option” or “Reid option” (the latter after the Nevada Senator who oversaw the rule change). Obviously, the party in a minority of more than 40% generally wants this kind of filibuster, because it basically means that the Senate needs 60 votes to pass something.
The Democrats currently have 41 votes against cloture of debate on the Gorsuch nomination. The “nuclear/Reid option” would be to allow his nomination to proceed to a vote by changing the rules–something the Republicans can do with zero Democrat support. Sure, the current procedures could be reinstated, but the party in power has little incentive to tie its hands that way.