Speculation is continuing to mount that Gordon Brown will call a November general election next week.
Mr Brown is expected to make a decision this weekend
The government says its Comprehensive Spending Review - which sets long-term spending plans - and pre-Budget report will be brought forward to Tuesday.
This is the last day on which Mr Brown can call an election for 1 November.
The CSR and PBR had been expected later in the month. Meanwhile, opinion polls suggest that Labour's lead over the Conservatives has fallen.
The two dates most widely touted for an election are 1 and 8 November.
Mr Brown is due to make a statement to the House of Commons on Iraq on Monday, the day MPs return from the summer recess.
Tuesday's CSR - only the second since Labour came to power in 1997 - will set out the government's spending policies and priorities for the next decade or so.
And, in the pre-Budget report, Chancellor Alistair Darling is thought likely to downgrade the forecast for the growth of the UK economy in 2008.
Mr Brown is expected to study the opinion polls over the weekend before announcing his decision on a possible election.
He has not ruled out holding an autumn poll and both Tory leader David Cameron and Lib Dem leader Sir Menzies Campbell have urged him to "bring it on".
Shadow chancellor George Osborne challenged Mr Brown not to "bottle" calling an election, saying he had "let his aides stoke up that speculation".
But Transport Secretary Ruth Kelly said: "When I heard David Cameron say, 'bring it on', I just had one thought - be careful what you wish for."
Sir Menzies said: "He really has to come clean and tell Parliament and the country what his intentions are.
"What began as a tease of the opposition parties a few weeks ago by the government has really turned into an abuse of the constitutional process and it's high time the prime minister brought the uncertainty to an end."
An ICM poll for the Guardian newspaper indicates that Conservative and Labour are level - on 38% - compared with a 7% lead for Labour one month ago.
The poll surveyed 1,008 adults on Wednesday and Thursday, after David Cameron's address to the Conservative conference in Blackpool.
Meanwhile, the results of an earlier YouGov survey for Channel 4 News - which interviewed 1,741 people, also on Wednesday and Thursday - suggested the government, on 40%, was four points ahead of the Tories compared with a lead of 11 points last week.
And a Populus poll for the Times, for which 803 adults were interviewed by telephone on Tuesday and Wednesday, indicated a three-point lead for Labour, on 39%, down from 10 points a week ago.
BBC political correspondent James Hardy said Mr Brown had been tested by floods, foot-and-mouth and terror threats but that his biggest test - whether or not to call a general election - was still ahead of him.
While Mr Brown had dominated the polls in his 100 days as prime minister, the Tories appeared to have bounced back, he added.
But a further 32% of those questioned called for Mr Brown to wait until 2008 before calling an election.
In its poll for Channel 4 News, YouGov also asked whether an autumn election was in Britain's best interests.
It found 36% thought it was, compared with 29% last week.
Asked if the prime minister should delay a nationwide vote until 2009, 7% agreed.
And another 7% said that waiting until 2010, at the end of the government's current five-year term, would be their preference.