The Institute of Fundraising is lobbying members of the House of Lords before a debate over the possible abolition of the edited electoral register.
Lord Michael Wills will lead a debate on government policy on electoral registration in the Lords on Thursday.
Louise Richards, director of policy and campaigns at the IoF, is lobbying a number of peers in advance of the debate. It is strongly against abolition of the register and been warning for some time that the Ministry of Justice is likely to abolish it.
The register does not contain details of people who have opted out of receiving marketing materials and is available for general purchase. It is used by many charities in their fundraising.
Richards said the IoF had sent an email outlining its concerns to lords that took part in a previous debate on the matter in 2009.
She said it had also forwarded them copies of a letter it sent in November to Nick Clegg, the Deputy Prime Minister, and Mark Harper, the Minister for Political and Constitutional Reform, which gave further details about their concerns.
"We strongly believe that the edited register should not be abolished," the letter said. "This data enables charities to fundraise more effectively and can help to reduce junk mail.
"The accuracy facilitated by the electoral register helps charities to fundraise more effectively in terms of stewardship. If charities are unable to verify the address accurately, there is more chance of mail being addressed wrongly, which can reduce potential donors’ inclination to donate."
The debate follows the publication of a report by the Politics and Constitutional Reform Committee in November, in which MPs recommended the register be abolished.
"Whatever benefit it might bring, we cannot justify the sale to commercial organisations of personal details gathered by the government for electoral purposes," the report said.
The Cabinet Office is due to respond to the report in due course.