President Trump called on Senate Republicans to invoke the "nuclear option" to scrap the filibuster and end the government shutdown. The Senate's rules require most legislation to attract 60 votes in order to advance, but changing the rules only requires a simple majority. Eliminating the filibuster would allow Republicans to approve the House-passed continuing resolution without Democrats and reopen the government, but most GOP senators have long been opposed to doing away with the 60-vote threshold, arguing that it encourages bipartisan compromise.