Several groups asked to be exempted from the nation's new campaign finance law Wednesday as elected officials solicited advice on how to enforce the restrictions on political ads.

The law, due to take effect after the Nov. 5 elections, will bar many groups from airing ads identifying federal candidates within 30 days of a primary and 60 days of a general election.

The Sierra Club Foundation and the Alliance for Justice, an association of civil rights, environmental, mental health, consumer, women's and children's advocacy groups, have joined forces to ask the Federal Election Commission to exempt organizations like theirs.

They made the request in written comments to the FEC on the commission's proposal to enforce the new ad restrictions. The Alliance for Justice planned to elaborate Wednesday at the first of two days of commission hearings on the subject.

Donald McGahn, an attorney for the National Republican Congressional Committee, told the commissioners that constitutional free speech issues must be foremost in their minds as they write the rules.

"This affects everyone up and down the ticket," McGahn said. "This affects every campaign in America."

The law's backers contend many groups have been using phony "issue ads" to get around a ban on the use of corporate or union money to influence federal elections. Such ads mention a federal candidate but do not directly call for his or her election or defeat.

The Alliance and the Sierra Club Foundation contend the new ad restrictions shouldn't apply to public charities and private foundations airing lobbying ads that urge viewers to contact their members of Congress on key issues at election time.

Campaigns and political action committees, funded by limited, reported contributions, can still air ads mentioning federal candidates close to elections but will face tougher disclosure standards under the new law.

Several commissioners said their biggest challenge would be deciding which speech their rules should regulate. They asked whether the new restrictions should apply to the mention of a federal candidate by a minister during a televised church service or by a comedian in a monologue on late-night TV around election time, for example.

Michael Malbin, executive director of the Campaign Finance Institute, a nonprofit, nonpartisan organization affiliated with George Washington University, suggested applying the restrictions only to paid advertising.

Glen Shor, an attorney with the Campaign and Media Legal Center, which supports the new law, said he was concerned about such an approach. Shor warned it might lead corporations and unions to finance elaborate public service announcements to support or attack federal candidates without falling under the new rules.

The political ad rules are among the most controversial features of the law, which also bans national party committees from spending corporate and union donations.

The National Rifle Association, AFL-CIO and U.S. Chamber of Commerce are among those suing to try to overturn the law, arguing it violates free-speech rights.