Updated

Federal election regulators refused to ease limits on political advertising Tuesday, blocking an effort to let interest groups run radio and television ads mentioning elected officials within weeks of an election.

The Federal Election Commission voted 3-3 on a proposal that would have allowed such ads as long as they addressed public policy issues and did not promote, support, oppose or attack a sitting member of Congress. Supporters of the change said they wanted to strike a balance between campaign ad restrictions and constitutional free speech guarantees.

The measure failed on a tie vote with the commission's three Democrats voting against the proposal and the three Republicans backing it.

With 70 days left before this year's general election, the change could have let loose a wave of unrestricted ad spending in the weeks leading up to Election Day. The vote lets stand a provision in the 2002 campaign finance law that requires independent groups to limit the contributions and to disclose the donors of money used to pay for ads that run within 30 days of a primary or 60 days of a general election.

Advocates of the change ranging from the U.S. Chamber of Commerce to unions to the ACLU argued that the law not only restricted campaign advertising but also prohibited interest groups from voicing their views on legislation before Congress.

Critics, including the congressional authors of the 2002 law, complained the change would create a loophole for secretly financed ad campaigns.