Democrats continued to hammer the U.S. Chamber of Commerce for campaign financing, with Democratic National Committee Chairman Tim KaineTimothy Michael KaineAuthorizing military force is necessary, but insufficient Week ahead: Crunch time for defense bill’s cyber reforms | Equifax under scrutiny Insurer Anthem to cover bare ObamaCare counties in Virginia MORE accusing Republicans of turning the campaign back toward the Watergate era.

On MSNBC, Kaine accused the GOP of "running a concerted effort to hide their donors for the American public."

Democrats have seized on allegations that foreign money is helping fund campaign ads from organizations such as the Chamber. White House senior advisor David Axelrod said last Sunday that it was up to the Chamber to disprove those claims.

"The Republicans have made a concerted effort this cycle to funnel as much of the campaign financing as possible to secret groups," Kaine said. "By doing that, they've turned back on 35 years of development that came out of the Watergate scandal towards openness and transparency."

"...We're pointing this out because we think the polling suggests — but more important, the right and wrong of this suggests — that the Republicans are pushing a secret agenda," Kaine added on Keith Olbermann's "Countdown" show.

Kaine claimed that all DNC funds "come from individuals — we don't raise money from corporations, PACs or federal lobbyists, and we're raising more money than we've ever raised in our history in the midterm elections."

Kaine added that polling was on the Democrats' side when pushing the campaign finance issue.