ABC News’ Rick Klein reports: The press is on to convince moderate Democrats to support health care reform — but it's liberal groups who are making some of the loudest noise on the eve of the vote. MoveOn.org today sent an e-mail to its members, asking for pledges of support for “progressive primary challengers” to Democrats who vote against President Obama’s initiative. “Health care reform is in serious danger in the House of Representatives: with a handful of conservative Democrats wavering, we don't yet have the votes to pass the final bill,” the e-mail reads. “So we're asking every MoveOn member: will you pledge to support progressive primary challengers to House Democrats who side with Republicans to kill health care reform?” “With the big vote happening as early as this Friday, conservative Democrats need to know the stakes if they choose to side with Big Insurance over the voters on health care reform. Our pledge will send that message loud and clear. We'll publicize the amount pledged, and make sure the media and every wavering representative know about it.” Also, a coalition of liberal groups — Progressive Change Campaign Committee, Democracy for America, and Credo Action — today is launching a TV ad in House Speaker Nancy Pelosi’s hometown of San Francisco, pressing her to reverse course and include a “public option” in the health care bill set for passage in Congress. “The Senate has the votes. The public option is in Pelosi’s hands,” the ad states. Pelosi said last week that a public option wasn’t being included “because they don’t have the votes to have it in there” in the Senate.