From Wikipedia:
United States
Donald Trump expressed interest in withdrawing from the organization during his 2016 presidential campaign. However, after he was inaugurated in 2017, he stated that the United States would protect allies in the event that Article V is invoked.[70][71][72] Nevertheless, the New York Times reported in 2019 that a year earlier, he had already mentioned several times privately that he wanted the United States to leave NATO due to many members not paying the required 2% of GDP funding.[73] Such concerns led the House of Representatives in January 2019, to pass the NATO Support Act (H.R. 676), confirming Congress’ support for NATO and prohibiting Trump from potentially withdrawing from NATO.[74] On December 11, 2019, the Senate’s Foreign Relations Committee passed a bill to be put in front of Congress which would require congressional approval for American withdrawal from NATO.[75][76]
Polling conducted by Pew Research Center in 2017, said that 62% of Americans are favorable to NATO compared to 23% who are not favorable. In terms of voters, over three-quarters of Democrats are favorable with just 48% of Republicans favorable. Also they said that a plurality of those surveyed, 47% said NATO does too little globally.[14] In further polling in 2019 on the eve of the 70th anniversary of NATO’s founding, 77% of Americans say being a member of NATO is good for the United States.[77]
While both major parties support NATO membership,[78] all the major third parties including the Green Party,[79] the Libertarian Party,[80] and the Constitution Party[81] support withdrawing the United States from NATO.