The Prime Minister and the Taoiseach will discuss plans for pressing ahead with the framework for a settlement in Ulster, without Sinn Fein.
After the meeting, expected to last an hour at No 10, the two leaders will go to the England-Ireland rugby match at Twickenham.
Their show of unity is intended to increase the pressure on the IRA and Sinn Fein to signal next weekend at the Sinn Fein annual conference a response to the declaration.
However, there are differences between the two governments which Mr Major and Mr Reynolds will have to resolve. They are split over the powers to be given to cross-border boards on services such as transport, energy, and tourism.
Mr Reynolds will be urging Mr Major to give the boards substantial powers as free- standing executive agencies. The British government is seeking to limit their powers to advising the two governments and an elected assembly.
That is regarded as insufficient for Mr Reynolds, who is keen to secure constitutional changes radical enough to undermine support for Sinn Fein. Mr Major and Sir Patrick Mayhew, the Secretary of State for Northern Ireland, are playing a balancing game with their own backbenchers and the Ulster Unionists.
Mr Major has been warned privately by Tory MPs who want to protect the Union that the cross-border boards could wreck the declaration.
'Some of my colleagues are worried that the boards are the first step towards a united Ireland,' one MP on the left of the party said. 'I think they should be given executive powers, and made answerable to the two parliaments.'
Sir Patrick told MPs yesterday that the boards could be made answerable to the two governments, the assembly, or the two parliaments.
Cabinet ministers remain pessimistic about Sinn Fein agreeing to peace. 'Gerry Adams (Sinn Fein president) doesn't want a split in the IRA. Every time that has occurred in the past, there has been feuding within the IRA and he does not want that to happen again. It looks as though he cannot persuade the army council and he doesn't want a split,' one source said.
Sir Patrick underlined the importance of the three-strand talks between the democratic parties. 'It is very important that that should continue . . . Nobody is waiting in the sense that some policy has been put in abeyance upon a Sinn Fein decision,' he said.Reuse content