Under the system, the public can register to stop sales and marketing organisations, including charities, making unsolicited calls to their homes. Only political parties are exempt.
Hugh McCaw, chief executive of fundraising consultancy Relationship Marketing, said he was talking to a group of politicians about exemption.
One option could be to offer people the choice to allow calls from charities but not from commercial organisations, he said.
"The public should have the right to choose and at the moment they can't," he said.
One of the politicians involved is Janet Anderson, Labour MP for Rossendale and Darwen, who is understood to be talking to charities minister Kevin Brennan about the matter.
When contacted by Third Sector, Anderson said the issue was a private matter and declined to comment.
McCaw said the TPS had affected fundraising by small and medium-sized charities because it had depleted their telephone databases.
"The Government is asking how it can help charities during this downturn," he said. "Maybe it could 'switch on' more than 10 million households in the UK to allow them to actually speak to the charities."
A Cabinet Office spokeswoman said it would look into any recommendations about the TPS.
The current Telephone Preference Service law came into effect in 2003.
Charities are subject to it, but political parties are not. Charities are exempt from a similar scheme in the US.
People cannot opt to allow charity calls unless they contact the charities directly.
Mobile phone numbers can be registered, but the service stops only phone calls, not texts.