Donald Trump’s fellow Republicans in the US Senate on Friday took the atypical rebellious step of overriding his veto for the first time in his presidency. The Senate pushed through a bill on defense spending against Trump’s strong objections – just 20 days before he leaves office. Meeting in a rare New Year’s Day session, the Senate secured the two-thirds majority needed to override the veto with bipartisan support two days before a new Congress will be sworn in on Sunday. Eight previous vetoes of legislation have been upheld. Under the US constitution, the president has the power to veto a bill passed by Congress, but lawmakers can uphold the bill if two-thirds of both the House of Representatives and the Senate vote to override it. The Republican-led Senate, following the Democratic-controlled House on Monday, passed the measure without Trump’s support, voting 81-13 on Friday afternoon. Overriding Trump’s veto marks a striking departure for GOP senators, who have largely stood by the president during his turbulent White House term. But Trump’s objections to the bill angered lawmakers, who had labored for months to put together a bipartisan bill and pride themselves on passing the military bill each year for 60 years, and voted to ignore his opposition to it. The $740bn National Defense Authorization Act (NDAA) determines everything from military programs and construction projects to how to address geopolitical threats. Trump refused to sign it into law because of its failure to repeal Section 230, a federal law that provides a legal liability shield for internet companies, and because it includes a provision stripping the names of Confederate generals from military bases. “We’ve passed this legislation 59 years in a row. And one way or another, we’re going to complete the 60th annual NDAA and pass it into law before this Congress concludes on Sunday,” Senate leader Mitch McConnell said. As votes were being counted indicating Trump had lost the battle, the president tweeted, touting a protest planned in Washington on Wednesday when the new Congress officially tallies the electoral college votes certifying Democrat Joe Biden’s presidential victory in November’s election.