David Cameron will unveil the rest of his new government - and risk angering senior Conservatives forced to make way for their Liberal Democrat coalition partners.
After announcing his Cabinet on Wednesday night, the Prime Minister will chair its first meeting on Thursday morning as he seeks to demonstrate he is getting down to business.
But he will also be filling out the middle-ranking and junior roles in the Tory-Lib Dem administration.
The new Cabinet features five Lib Dems, including Deputy Prime Minister Nick Clegg, Business Secretary Vince Cable, Energy Secretary Chris Huhne, Treasury Chief Secretary David Laws and Scotland Secretary Danny Alexander.
Former Tory leader Iain Duncan Smith has also been awarded the job of Work and Pensions Secretary in what is being seen as a sop to the right of the party amid concerns about the alliance with the Lib Dems.
The appointments meant some senior Tories were not given full Cabinet positions, including Chris Grayling, Dominic Grieve and Theresa Villiers.
Another 15 Lib Dems are expected to be appointed to the lower ranks of the Government, creating even more pressure for places.
After five days of horse trading following the inconclusive general election result, the work of government is finally getting under way again.
Mr Cameron, Mr Clegg and other senior Cabinet ministers attended their first meeting of the Government's new National Security Council on Wednesday night, joined by the Chief of the Defence Staff, Air Chief Marshal Sir Jock Stirrup, new National Security Adviser Sir Peter Ricketts and intelligence chiefs. Ministers were briefed on the situation in Afghanistan and counter-terrorism work in the UK.
Foreign Secretary William Hague will meet US secretary of state Hillary Clinton in Washington on Friday in his first overseas visit in the job. "I think getting to grips with these Afghanistan and Iranian issues is right at the top of our agenda," he said. A visit to Europe would follow "very quickly", he added.