WASHINGTON (CNN) - MoveOn.org, a grassroots powerhouse that supports Sen. Barack Obama for the Democratic presidential nomination, launched a fundraising drive Thursday to counter Sen. Hillary Clinton's wealthy supporters.
Her supporters have recently argued with their checkbooks that superdelegates should vote their conscience at the Democratic National Convention in August.
MoveOn's drive sets up a face-off that illustrates the widening gap in the Democratic Party between some of its traditional financial backers, many of whom support Clinton, and a Netroots donor base that leans toward Obama.
Twenty of Clinton's major donors sent a letter to House Speaker Nancy Pelosi Wednesday that suggested they might rethink their support for the party's congressional efforts this cycle if Pelosi did not alter her publicly stated view that superdelegates should support the party's pledged delegate leader - a position that would be fatal to Clinton's presidential bid.
"We have been strong supporters of the DCCC," they wrote. "We therefore urge you to clarify your position on superdelegates and reflect in your comments a more open view to the optional independent actions of each of the delegates at the National Convention in August."
The DCCC - Democratic Congressional Campaign Committee - assists the party's House candidates.
A day later, MoveOn.org announced its fundraising drive to demonstrate its support for Pelosi's position
"It's the worst kind of insider politics - billionaires bullying our elected leaders into ignoring the will of the voters," wrote organizers in an e-mail to the group's members. "But when we all pool our resources, together we're stronger than the fat cats. So let's tell Nancy Pelosi that if she keeps standing up for regular Americans, thousands of us will have her back. And we can more than match whatever the CEOs and billionaires refuse to contribute."
Senior advisers to Clinton's campaign denied Thursday the campaign had anything to do with the donors' message to Pelosi.