A number of charities have changed their tactics in direct mail campaigns because of the general election, and some believe an influx of leaflets from political parties could harm the impact of their mailings.
Mark Roper, managing director of direct marketing agency Whitewater, said a number of charities had raised concerns that receiving a lot of political leaflets might make people less likely to notice their mailings.
"When the response rates come in for direct mail campaigns running at the moment, they could well be lower than expected," he said.
Monika Nariani, head of marketing for the MS Society, which has sent 165,000 pieces of direct mail and 750,000 door drops to mark its annual MS Week in late April and early May, said the charity was anticipating lower returns than usual.
"The election is likely to have some impact on our fundraising income, but by integrating the mailing with our other awareness-raising activities we hope it'll still stand out," she said.
"The appeal would do better if there wasn't an election, but we prepare our supporters all year for MS Week - not to contact them during this time would have felt wrong."
Vicky Crompton, a fundraising coordinator at homelessness charity Spear, said it had deliberately sent out a direct mail appeal because of the election, and would not have done so otherwise. "For the first time, people seem to be engaging with big social issues, and homelessness is one of these," she said. "People are debating things, so they could be more receptive to our message that we are dealing with the problem on the ground."