What to know about the 'nuclear option' and the U.S. Senate's filibuster fight

Capitol Hill is in a "nuclear" countdown, and the U.S. Senate is already bracing for the political fallout.

How do the rules work now?

A"supermajority"of 60 votes in the 100-seat Senate is currently required to invoke "closure." That's the process of ending a filibuster, which is the act of continuous debate on the floor to prevent a vote.

The filibuster is an important procedural device that empowers the Senate's minority. Once closure is imposed, the up-or-down vote can proceed.

What would the 'nuclear option' change?

It would blow up the filibuster of Supreme Court nominees. That's because it would drop the threshold to a simple majority of 51 votes, down from the 60-vote supermajority needed to reach closure.

"This literally changes the way the Senate operates," says Rachel Bovard,director of policy services for the Heritage Foundation, a Washington-based conservative think tank.

"In the Senate, the minority is incredibly powerful. The filibuster is one of the most important tools."

Republicans hold a slim majority of 52 seats in the Senate; Democrats have 46. (The remaining two seats are held by independents who caucus with the Democrats.) Without the filibuster, whichever party controls a razor-thin majority can steamroll the opposition and pass their choice of Supreme Court justice.

Why is a weaker minority such a big deal?

In the short-term, Bovard says, diminishing the minority position's powers in the Senate could clear the way for extreme ideologues to occupy seats on the Supreme Court bench.

"It goes back to this idea that the filibuster forces presidents to pick the nominee that will be acceptable to both parties."

Were it not for the filibuster,Trump "would have been able to pick a much more radically conservative justice, and would have gotten him through the Senate no problem," she says.

• ANALYSIS |Trump's party controls Congress, but he won't have free rein

By the same token, a future Democratic president with a Democratic-controlled Senate would have free reign to pick a liberal judge without having to answer to opposition conservative senators.

Senator Lindsey Graham of South Carolina warned that provokingRepublicans to go nuclear on Supreme Court nominees could end up haunting the upper chamber for generations.

"The judges are going to become ideological because you don't have to reach across the aisle to get one vote any longer," he said. "And every Senate seat is going to become a referendum on the Supreme Court."

What's the long-term impact?

Aside from Gorsuch, Trump could end up naming moreSupreme Court judges. Ruth Bader Ginsburg is 84, Anthony Kennedy is 80, and Stephen Breyer is 78, and they could be headed towardretirement.

Bovard, blaming the "culture shift" on a hyper-polarized political climate, worries the legislative filibuster could bein peril, too.

• U.S. Senate heads for showdown on Supreme Court nominee NeilGorsuch
• ANALYSIS | With Trump willing to 'go nuclear' over Supreme Court pick, filibuster could be shortsighted

"It's going to be a lot easier to nuke the legislative filibuster because they've already nuked everything else," she says.

A precedent ofeliminating the filibuster was set four years ago, when Democrats held a majority in the Senate and Democratic president Barack Obama was in the White House.

Why does 2013 matter?

Not long ago, deploying the nuclear option for Supreme Court nominations was considered off limits, but anescalation began in 2013.

Harry Reid, who was majority leader in the Senate at the time,urged Democratsto invoke the nuclear option so they could finally push through Obama's nominees for federal appeals-court judges and some executive-branch appointments.

Will they really 'go nuclear'?

"Judge Gorsuch is going to be confirmed,"McConnell has already vowed, strongly suggesting he has no qualms about executing the nuclear option.

He already has his marching orders from the president.

"If we end up with that gridlock I would say, 'If you can, Mitch, go nuclear,'" Trump told reporters in February.

Can't the rule be reversed?

Neither party is likely to want to roll it back once they take over majority in the Senate. McConnell, for example, could have undone the 2013 nuclear option instituted by Reid.

Democrats could, however, decide to save their filibuster for another occasion and avoid the "nuclear option" for now.

It's almost certain their efforts to block Gorsuch will fail, but some Democrats remain embittered about Republicans' refusal for nearly a year to even grant a hearing to Merrick Garland,Obama's Supreme Courtpick.

Others say they will filibuster Gorsuch because they found his testimony to be evasive and vague.

But doesn't 'nuclear' sound a bit extreme?

Not to the Senate. The "nuclear" terminology describes the explosive nature of the rule change, but also the tit-for-tat political warfare and the mutually assured destruction of the filibuster as a tool of the Senate.

As with nuclear war, no side truly wins.