What is the nuclear option and what does it have to do with Neil Gorsuch's nomination?

Supreme Court Justice nominee, Neil Gorsuch, center, is joined by Vice President Mike Pence, right, as they meet with Senate Majority Leader Mitch McConnell of Ky. on Capitol Hill in Washington, Wednesday, Feb. 1, 2017. Last year, Senate Republicans, led by McConnell, blocked a confirmation hearing for Judge Merrick Garland, President Barack Obama's pick for the vacancy left by the death of Justice Antonin Scalia who died in February 2016. (AP Photo/J. Scott Applewhite)