Senate Majority Leader Harry Reid is facing a challenge from so-called “moderate” lawmakers over his plans to include a government-funded public insurance option as part of healthcare reform. Reid said Monday he had settled on a compromise that would allow states to opt out of the public program. But on Tuesday, Senator Joe Lieberman of Connecticut said he would back a Republican filibuster if the public option is included. Lieberman is an Independent but caucuses with the Democrats. Republican Senator Olympia Snowe also renewed her opposition to the public plan. Several Democratic senators have refused to publicly support Reid’s measure, including Evan Bayh of Indiana, Mary Landrieu of Louisiana, Ben Nelson of Nebraska, and Blanche Lincoln and Mark Pryor, both of Arkansas.