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A broad proposal to limit spending by tax-exempt groups pouring millions of dollars into this year's elections is drawing a wide range of opponents including the AFL-CIO, (search) the U.S. Chamber of Commerce and the NAACP (search).

In addition to comment from the interest groups, the Federal Election Commission (search) received more than 140,000 e-mails after President Bush's re-election campaign urged supporters to write in favor of restrictions, and the pro-John Kerry (search) group MoveOn.org (search) asked its backers to oppose them.

The commission planned a two-day hearing on the proposal starting Wednesday.

At issue is whether groups raising "soft money" — corporate, union and unlimited donations — should be banned from spending it in presidential and congressional elections or face new rules on how much soft money they can use.

Campaign finance law bars the national political parties and federal candidates from raising soft money and broadly bans its use to influence federal elections; the question is how far the ban goes.

The FEC's decision, expected next month, could have a big impact on the fall elections.

Pro-Kerry groups including MoveOn and the Media Fund are spending millions of dollars in soft money on ads promoting Kerry or opposing Bush, chipping away at Bush's multimillion-dollar fund-raising advantage over the presumptive Democratic presidential nominee. Other partisan groups, mostly pro-Democrat so far, plan to use soft money on get-out-the-vote and other efforts in the presidential and congressional elections.

The Bush campaign accuses Democrats of forming a network of groups to serve as a "shadow party" and use soft money for election activities the Democratic Party can no longer pay for with big donations. The campaign sent an e-mail this week asking donors for more money "so we'll have the resources to counter their efforts."

The FEC is considering classifying soft-money groups that spend in federal elections as political committees, which would limit them to capped donations from individuals.

Hundreds of groups, including the Sierra Club, National Right to Life Committee and the National Education Association, argue that a cap would go beyond the law's soft money limits, free-speech rights and the commission's authority.

They contend the proposal would ban soft money-financed lobbying or issue-advocacy ads or nonpartisan voter drives that mention federal candidates in a favorable or negative light at any time. The law bans the use of corporate or union money for TV or radio ads targeting federal candidates in the weeks before an election.

Campaign finance watchdogs including the law's lead sponsors, Sens. John McCain, R-Ariz., and Russ Feingold, D-Wis., want restrictions for partisan soft-money groups whose focus is federal elections. They say issue groups should be left out.