Republicans say newly formed voter registration groups like Voices for Working Families (search), which are called 527 committees (search) after the section in the tax code in which  they operate, are funded by Democratic-leaning groups such as the AFL-CIO.

The Republican National Committee says Working Families is one of six groups nationwide illegally coordinating with John Kerry's campaign in order to defeat President Bush.

Activists deny the charge, and say they have no partisan bent.

"It's not a loophole, it's the law," said Alvin Anderson, a team leader for Voices for Working Families. "Non-partisan, non-profit."

Similar groups tell Fox News that they've signed up as many as 100,000 new voters — from predominantly Democratic neighborhoods in key battleground states.

The man who co-authored the McCain-Feingold campaign finance reform law (search) said these 527s are purely partisan and must be stopped.

"They're political operatives running outfits that are engaged in partisan political activities. There's no doubt about it, any objective observer would tell you that so therefore they should fall under federal campaign laws," said Sen. John McCain (search), R-Ariz.

Click here for a report by Fox News' Orlando Salinas.