Keir Starmer will whip Labour MPs to support Boris Johnson’s Brexit deal when it comes to parliament next week, he has announced, in a move likely to provoke a rebellion by pro-EU backbenchers. The Labour leader gave a press conference after the prime minister announced that negotiations had concluded, and said he had made the “tough decision” to back the agreement. “When this deal comes before parliament, Labour will accept it, and vote for it,” he said. Starmer described Johnson’s deal as “thin”, saying it would not underpin workers’ rights or adequately protect sectors such as manufacturing and the creative industries. But he insisted that a no-deal exit from the transition period on 1 January next week was now the only other realistic possibility. “A better deal could have been negotiated. But I accept that option has now gone,” he said. Some Labour MPs had urged Starmer to abstain in the vote on the deal, saying he would be unable to hold the government to account for its economic consequences if Labour had supported it. Others, including some of those who refused to vote to trigger the article 50 process of leaving the EU, would like Labour to vote against. Several shadow cabinet members – including the shadow chancellor, Anneliese Dodds, the shadow chief secretary to the Treasury, Bridget Phillipson, and the shadow international trade secretary, Emily Thornberry – are known to have expressed concerns about the idea of supporting the deal, though they are expected to abide by collective responsibility. Dodds tweeted on Thursday that the agreement would have a “major negative impact” on GDP and pointed out that it would not have the “exact same benefits” as EU membership – a promise that Starmer included as one of his “six tests” of Theresa May’s deal when he was the shadow Brexit secretary. But Starmer insisted that “leadership is about taking the tough decisions in the national interest”, adding: “It is about being a serious, responsible opposition. At a moment of such national significance, it is not credible for Labour to be on the sidelines.” Johnson attacked Starmer at prime minister’s questions this month when he abstained in a key vote on coronavirus restrictions. He said his message to the government was: “Up against no deal, we accept this deal, but the consequences of it are yours. And yours alone. We will hold you to account for it every second you are in power.” The decision was confirmed in a shadow cabinet meeting on Thursday. Both Houses of Parliament will be recalled on 30 December, with the Commons sitting from 9.30am and the Lords from noon, to push through a bill implementing the deal – potentially in a single day. The Speaker of the House of Commons, Lindsay Hoyle, has urged MPs and their staff to avoid travelling if possible, given the Covid restrictions in place in many parts of the country and the prevalence of the disease in London. With Labour’s support, even a significant rebellion by Eurosceptic MPs on the Tory benches – which appears unlikely – will not prevent the deal from passing. But Starmer may face a significant rebellion on his own side, with some Labour MPs suggesting scores of colleagues could defy the whips, who will be unable to use the traditional approach of face-to-face persuasion to win them over. The Liberal Democrat leader, Ed Davey, said his party had not yet decided how to vote on the deal, but he told BBC News: “Even on an early analysis, it’s looking a pretty poor deal for our economy.”