From: hosted.ap.org

That's the hardball message liberal groups are hurling at moderate Democratic senators in a battle that is dividing their party. Their demands: Support a bill that offers optional government-run health coverage and oppose Republican attempts to derail the legislation.

The groups are unleashing blunt and personal broadcast ads and e-mails at moderates even as Senate Majority Leader Harry Reid, D-Nev., tries to shape a health care bill that can attract the 60 votes it needs to pass. Assuming no Republican support, Reid needs backing from all 58 Democrats and both Democratic-leaning independents - including about a half-dozen moderates who have drawn liberals' ire.

It's all taking place a year out from elections in which Republicans hope to trim the Democrats' congressional majorities. The intraparty conflict especially threatens moderates facing tough re-election fights in 2010, like Sens. Blanche Lincoln, D-Ark., and Reid himself. It could mean less enthusiasm on the part of liberal and labor groups, which supply campaign workers, contributions and votes to Democratic candidates.

But liberal pressure has its limits in the conservative states that many moderate Democratic senators represent. At some point, attacks from progressives can amount to a benefit.

"Criticism from liberals is almost a political endorsement here," said Loree Bykerk, a political science professor at the University of Nebraska at Omaha. Moderate Sen. Ben Nelson, D-Neb., is among those targeted.