Labour and the Conservatives ran up millions of pounds in cash deficits last year as they prepared for the election, according to their accounts.
Electioneering proved an expensive process
The Lib Dems instead built up a pre-poll surplus of £444,665 - although this war chest is expected to be mostly exhausted by the end of this year.
The Tories had a £6.2m shortfall in 2004, taking their debts to an overall total of £13.1m.
Labour's pre-election spending produced an overall deficit of £2.8m.
The Electoral Commission published accounts for all the political parties for the year ending 31 December 2004.
It has agreed to extend the deadline for accounts from Respect, the Scottish Socialist Party, the British National Party's regional accounting unit and the south-east unit of the UK Independence Party.
The commission said it was "disappointed" by the delays.
The Scottish Socialist Party, the British National Party unit and the UK Independence Party unit were given until Friday to submit their accounts - originally due on 7 July.
An Electoral Commission spokeswoman said the BNP and UKIP units had both submitted their documents on 29 July ahead of the extended deadline.
Respect has until the end of the month to submit its accounts.
The Tories are considering the future of Central Office
A Conservative source said the party was not desperately worried about its deficit.
Its debts were not in bank overdrafts but in "soft loans" lent either by Conservative local associations or by "very friendly donors" charging little or no interest.
The source said there was no question of the debts suddenly being called in and last year's deficit was not particularly high compared to other pre-election years.
The Tory insider also said the party was now spending no more than its income.
As they strive to fill their cash shortfall, the Tories may hope for a repeat of the upsurge in donations previously produced by a change in leader.
The party last year moved its headquarters from Conservative Central Office in Smith Square to nearby modern offices in Victoria Street.
In the accounts, Tory Treasurer Jonathan Marland says: "We are now reviewing our options as to our future at Smith Square."
It is understood a feasibility study on the future of the £10m building will soon go before the Conservative board.
Options in the paper include selling the building, or the party returning to the offices.
The Tory accounts also show that Lord Saatchi's advertising companies, The Immediate Sales Company and M&C Saatchi, charged £339,000 and £207,000 respectively in 2004.
The bills follow a £19,000 payment to The Immediate Sales Company in 2003.
Lord Saatchi also gave the party £6,000 last year.
After the election, Lord Saatchi penned a damning verdict on the Tory poll campaign, saying he had failed to convince the party that it needed to stand for something.
In his report for the accounts, current Conservative Party chairman Francis Maude said Tory membership numbers had increased so the party now had "more members than both Labour and the Liberal Democrats combined".
Labour's accounts say the party's membership levels fell but "at the lowest rate since 1997".
In 2004, 17,000 new members were signed up, it says.
There was also praise for Deputy Prime Minister John Prescott for his efforts in spearheading "extremely successful" campaigns to return former members to the party.
For the Lib Dems, Treasurer David Griffiths says the party reduced its historic deficit to £134,000.
By the end of last year, the Lib Dems had a campaign fund totalling £780,000.
"Although the party has never been in a stronger financial position in the run-up to a general election it is expected that this fund will be largely exhausted by the end of 2005," added Mr Griffiths.