This week, the U.S. Senate will vote on whether to accept Donald Trump's nomination for the Supreme Court.

　　The president has asked Congress to approve federal judge Neil Gorsuch, who is 49 years old.

　　If he is approved, Gorsuch will fill the position that has been open since February 2016, when Justice Antonin Scalia died. Under the U.S. Constitution, the president nominates Supreme Court Justices, and Congress decides whether to approve them.

　　If Gorsuch is approved, he will be permitted to stay on the Court for the rest of his life, and to help determine the meaning of the country's laws -- including on disputed issues related to guns and abortion. He would restore the 5-4 conservative majority before Scalia's death.

　　In the days leading up to the Senate's decision, many people are arguing about the vote. Two words especially are coming up: filibuster and nuclear option.

　　Democrats, who in general do not support Gorsuch, are threatening to filibuster. And Republicans, who support him, are threatening to use the nuclear option.

　　But what do these words mean?

　　The filibuster

　　A filibuster is a way of delaying a vote. The political party with the smaller number – or minority – in Congress can use it to prevent lawmakers from voting.

　　The filibuster has been part of Senate rules since the 1800s.

　　Historically, senators filibustered by speaking for many hours -- often overnight -- to block votes.

　　For example, during the 1930s Senator Huey Long of Louisiana spoke against bills he said favored the rich over the poor. Once he talked for 15 hours, the Senate Historical Office says. Long filled the time by reading from William Shakespeare's plays and sharing his favorite food recipes.

　　Now, senators do not usually talk continuously to filibuster. Instead, they insist that the majority party come up with 60 votes to end debate and schedule a vote. If the majority party falls short of 60 votes, the vote is blocked.

　　Democrats, who are in the minority party in the Senate, say they will filibuster the vote on Gorsuch.

　　The nuclear option

　　But Republicans who want Gorsuch to start hearing cases right away are preparing to counter the Democrats' move.

　　Under Senate rules, lawmakers can stop a filibuster. If 60 out of the 100 senators agree, debate can be stopped and a vote scheduled.

　　But Republicans do not have the 60 votes to stop the Democrats' filibuster. Only 52 of the lawmakers are Republicans and not enough Democrats will support their move to stop the filibuster.

　　And that explains why Senate Republicans say they will use the "nuclear option."

　　In this case, the phrase means to change a rule in the Senate. Republicans will move to change a rule that would allow a simple majority of senators to end debate and schedule a vote. A rule change only requires a majority vote.

　　Why is it called the nuclear option?

　　This change in Senate rules was first described as the "nuclear option" back in 2003.

　　The reason: Some compared a difficult political situation in the Senate to the Cold War between the U.S. and the former Soviet Union. It was said that nuclear deterrence -- that both nations had enough nuclear weapons to destroy the other -- meant neither country was likely to attack the other.

　　Gregory Koger teaches political science at the University of Miami in Florida.

　　As was the case with the Soviet Union and the U.S., Koger said, Democrats and Republicans know the party that approves the "nuclear option" will pay a price. For Republicans, it will come when Democrats reclaim the Senate majority and are able to confirm Supreme Court justices with a simple majority.

　　Koger said the Senate has long worked on the common belief that "nobody gets everything they want," and that compromise is needed to get things done. A vote to end the filibuster for Supreme Court judges, he said, "signals the end of that way of doing things."

　　Why are we in this situation?

　　The current fight over the Gorsuch nomination goes back to the Obama administration.

　　Republicans blocked votes on many judicial and administration nominees from President Barack Obama, a Democrat, particularly in his second term.

　　Senate Democrats responded by changing Senate rules in 2013. No longer would 60 votes be needed to end a filibuster against judicial nominees and top positions in the government.

　　But the filibuster remained available for Supreme Court nominations -- a rule Senate Republicans are ready to change this week.

　　Republicans took over the Senate majority from Democrats in 2015. And in 2016, Republican leaders refused to hold hearings or vote on Obama's final nominee for the Supreme Court, Judge Merrick Garland. Republican leaders said the choice should go to the next president.

　　And now Trump, a Republican, is president. Less than two weeks after taking office, he chose Gorsuch for the Supreme Court.

　　I'm Bruce Alpert.

　　And I'm Dorothy Gundy.

　　Bruce Alpert reported on this story for VOA Learning English. Kelly Jean Kelly was the editor.

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