Boris Johnson will appoint new ministers to his cabinet on Monday as he pushes ahead with Brexit after securing a historic victory in last week’s U.K. election.

The prime minister now has the power to enforce his vision for leaving the European Union and reshaping the British economy, following the biggest win for his Conservative Party since Margaret Thatcher 32 years ago.

He needs to fill the roles of culture secretary, Welsh secretary and environment minister, which were vacated after Nicky Morgan quit politics, Alun Cairns was forced to resign and Zac Goldsmith lost his seat. His next task will be to complete the U.K.’s divorce from the EU by the end of January.

After Brexit, a more sweeping reorganization of government is likely. An official familiar with the matter said that the Brexit department will be scrapped. The Sunday Times reported that the energy and climate change department—abolished by Johnson’s predecessor, Theresa May—will be recreated, with the business and international trade departments merged.

After three years of chaos following the 2016 vote to leave the European Union, Johnson redrew the U.K.’s electoral map with a resounding victory over Labour in the Dec. 12 vote. Now he has a large parliamentary majority, he is the master of the political landscape in London.

Scottish Revolt

But Johnson faces a longer-term battle to keep the U.K. together once it leaves the EU. Scotland is already starting a fresh debate about splitting away from the rest of the country.

Last Thursday’s election saw the Scottish National Party strengthen its grip north of the border, taking districts from Johnson’s Tories with promises to oppose Brexit and campaign for another vote on independence.

SNP Leader Nicola Sturgeon—who is first minister of Scotland—says the election now gives her a mandate for a fresh referendum on whether to become an independent country, after voters chose to stay part of the U.K. in 2014.

Scotland “cannot be imprisoned” in the U.K. “against its will,” Sturgeon told BBC TV on Sunday. “If the United Kingdom is to continue, then it can only be by consent.”

On Sunday, Johnson’s team gave its most emphatic rejection of Sturgeon’s demand so far, ruling out a second Scottish independence referendum. “We are not going to have an independence referendum in Scotland,” Cabinet Office Minister Michael Gove told Sky News. But the argument is unlikely to go away.

Brexit First

Johnson, meanwhile, plans to plow on with taking the U.K. out of the EU by the Jan. 31 deadline. His office said he will introduce a law to deliver Brexit before Christmas. This will be the government’s first priority.

Johnson will name his senior cabinet team on Monday as he welcomes 109 new Conservative members of Parliament to London to take their seats in the House of Commons.

On Thursday, he will announce his program for government in a Queen’s Speech building on the agenda put forward in October. The monarch will make a new speech outlining the plans, which include a bill to enshrine in law an extra 34 billion pounds ($45 billion) per year of pledged spending on health care by 2024. The NHS became a crucial battleground during the election and Johnson has said he is determined to honor his pledges to voters to safeguard state health care.

While the prime minister pushes ahead with his plans, the main opposition Labour Party is gearing up for a leadership battle that’s likely to pit candidates loyal to the defeated leader Jeremy Corbyn against more moderate MPs who want to reclaim the political center ground.

Labour finance spokesman John McDonnell said the party will have a new leader before elections in London and local districts next May. He touted the party’s spokeswomen for business, education and women, Rebecca Long-Bailey, Angela Rayner and Dawn Butler as potential candidates, as well as justice spokesman Richard Burgon. Backbencher Lisa Nandy told the BBC on Sunday that she’s “seriously” thinking about running.