Tony Blair and Gordon Brown are staying in constant touch as the countdown begins to the government's long-awaited statement on the euro.
Cabinet ministers have come to a decision on the UK's membership of the euro, after a special meeting lasting more than two and a half hours.
The chancellor said a decision had been taken on the basis of the "national economic interest" - comments widely interpreted as confirmation that he will say the conditions are not yet right for Britain to join.
But Britain has to wait until Monday to hear Mr Brown announce the Treasury's assessment of the government's five economic tests in the House of Commons.
The prime minister's official spokesman said Mr Blair and the chancellor "will continue to talk on a daily basis as they have done for the last few weeks".
The spokesman said there was "unity around the cabinet table" and the talks on Thursday had been "very constructive".
"It marked the end of a very thorough and detailed process which the prime minister, the chancellor and the cabinet have valued greatly," he said.
Mr Brown said: "We are all resolved that the decision on the euro must be taken in the national economic interest, and it will be the national economic interest that
will be the determining factor.
"We are all resolved that nothing must be done that will put the stability of
the British economy at risk. Indeed we want to entrench that stability for the
long term for Britain."
The UK's five tests
Convergence with eurozone
Enough flexibility to adapt
Impact on jobs
Impact on financial services
Impact on foreign investment
Mr Brown said all the relevant documents, including the 1,800 pages of the Treasury's 18 background studies and a 250-page final assessment, would be published on Monday so voters could look at the background to the government's decision.
He said he hoped it would lead to an "open and widespread" debate
in the country at large.
Meanwhile, speculation is mounting that he will announce the government will publish draft legislation to pave the way for a possible referendum.
Splits?
But shadow chancellor Michael Howard said Monday's decision would simply be a reflection of who emerged the victor in a "bitter" row over the issue at the heart of the cabinet.
"What we hear won't be decided on the basis of Britain's national economic interest, it will be based on the outcome of the furious factional infighting that is tearing this government apart," he said.
At Thursday's meeting, ministers looked at major issues surrounding the euro such as the housing market, jobs and inflation.
It is believed the Treasury's assessment of the euro says that not all its five economic tests have been met - ruling out a referendum on the currency this year.
The big question is whether the final decision will leave open the possibility of a poll during the next two years, and ahead of the next general election.
Election on way
Mr Brown is said to favour putting off a poll until after the election, while Mr Blair is said to be ready to put off the general election until 2006 to allow for the euro vote.
BBC political editor Andrew Marr said he doubted a referendum would happen before an election.
If Tony Blair still really wants to get this country into the euro, he's going to have to fight a general election and win it first
The BBC's Andrew Marr
"The truth of the matter is that next year, Britain is going to be convulsed by this very, very difficult and controversial decision about the European constitution.
"And the year after that we're heading towards the general election.
"After delaying for six years it's quite hard to see this government suddenly rushing it... effectively, if Tony Blair still really wants to get this country into the euro, he's going to have to fight a general election and win it first."