The Labour Party said bookings from the sector were up 50 per cent for its conference in Manchester, starting on 20 September. Last year, 220 organisations attended; this year, 330 are expected. The Conservatives said they were expecting more than 500 charity representatives, which would be a 35 per cent increase on last year. No figures were available from the Liberal Democrats.
Umbrella body the NCVO, which runs a bursary scheme for organisations with incomes of less than £100,000 to enable them to attend party conferences, said the figures indicated a massive rise in interest.
"Despite the tightening economic climate, charities are looking to lobby and interact with the main political parties, possibly because of the increased likelihood of a general election," said Chloe Stables, parliamentary and campaigns officer at the NCVO.
With an election in 2010 or sooner, next year could be too late for charities to start influencing manifestos.
Simon Hebditch, a charity consultant and former chief executive of Capacitybuilders, said: "We are really into an election period from now until whenever.
"Charities will want to take every opportunity they can to get their messages over and they see the party conferences as part of that.
"This year and next year will be vitally important, and that is reflected in the number of charities attending party conferences." WHY THEY'RE GOING - OR NOT
With each conference attracting more than 10,000 delegates, they represent a great opportunity to promote our work to ministers, opposition spokespeople, councillors and party members
Alison Worsley, assistant director of policy and public affairs, Barnardo's
- We used to hire exhibition space and hand out literature, which was expensive and ineffective. We now host fringe meetings, which enables us to have a real impact on the political agenda in Wales
Michael Phillips, media relations manager, Age Concern Cymru
- We're not going to any. The cost of attending is disproportionate to what we get out of it. Labour used to allocate free stall spaces to campaign groups, but that changed a few years ago and the fee shot up
Ann Feltham, parliamentary coordinator, Campaign Against Arms Trade.