UPDATE: A Huffington Post report Friday indicates that Democrats believe they are one or two votes shy of having a filibuster-proof majority to pass a public health insurance option.

More here. The names of those who aren't on board for a filibuster is unknown, but at least one senator's office -- that of Florida Sen. Bill Nelson (D-FL), wouldn't say how the senator will vote.

Support for including some version of a public option in the Senate's version of a healthcare overhaul appears to be solider than initially believed.

In a series of comments that have received little attention, conservative Democratic senators -- even those who've publicly said they oppose a public option -- say they are unlikely to join a Republican filibuster to block it. Under Senate rules, Democrats would need to convince 60 members to support the ability to vote on healthcare legislation with the public option (cloture), and then just 51 to pass it.

Sen. Mary Landrieu (D-LA) told a reporter earlier this week that she wouldn't join Republicans in voting against cloture.

"I'm not right now inclined to support any filibuster," Landrieu said.

"For the Republican Party to kind of step out of the game is very unfortunate," she added, referring to the Senate Republicans' intransigence on healthcare reform proposals. "I'm not going to be joining people that don't want progress."

Indeed, Landrieu's sentiment -- that joining foes of healthcare reform would be an impediment to progress -- may be the catnip that keeps Democrats on board.

Sen. Mark Pryor (R-AR), a moderate Democrat from the South, said Thursday he was open to some form of a government-run health insurance competitor.

"It depends on how it's structured on whether I can support it," Pryor remarked. "I just haven't decided."

But regardless of how he votes on the final package, he says he won't join Republicans in filibustering the bill. Tellingly, he also signaled that he didn't believe any other Democrats would either.

"I don't think you'll see me or any other Democrats do that," Pryor told liberal blogger Mike Stark.

One conservative Democrat refused to tip his hand. Nebraska Sen. Ben Nelson (D-NE) occasionally joins Republicans on controversial issues.

"I believe in playing chess, but that's about three moves ahead of me, and I'm not prepared to make those moves until I see some other moves in between," Nelson told a reporter this week.

Jake Thompson, Nelson's Communications Director, told Raw Story  that he "would decline to comment" about how Nelson will react to a potential Republican filibuster.

Arlen Specter (D-PA) has said he'll support a public option as well. Specter defected from the Republican Party to the Democrats earlier this year, against the backdrop of a tough primary challenge from his right. In an interview Thursday evening with MSNBC's Ed Schultz (video below), he sounded confident that Democrats had the 60 votes to prevail.

"We have 60 votes without Sen. Snowe, so we can still invoke cloture and move to a vote on the public option," Specter said. "With 50 votes plus the Vice President and my vote is going to be for the public option, robust public option, we can get it passed, even without Sen. Snowe. I hope we have her, but we may be able to do it without her."

Sen. Olympia Snowe (R-ME) was the only Republican to join ranks with Democrats in approving a version of healthcare legislation that passed through the Senate Finance Committee. That version didn't include a public option.

That said, Democrats need lose only one member to lose the battle for the public option. A 60-vote majority would also need to include independent Sen. Joe Lieberman (I-CT), who's tangled with Democrats on various issues in the past.

Senate Majority Leader Harry Reid (D-NV) won't say how many votes he has in his arsenal on a government run plan. In a statement Thursday evening, he said only that he was looking to pass a bill with as many votes as possible.

"We'll continue to work together to seek broad consensus on the key issues before us and to craft the strongest possible bill that can garner 60 votes," Reid said. "We will also continue to do our best to represent the views of all members of the Senate who have a genuine desire to see reform succeed. But our mission is clear: the American people want quality, affordable health insurance and failure is not an acceptable option. I am optimistic that we are close to laying a proposal before the full Senate that will do just that."

In the House, some version of a public option is almost certain to pass. The version will likely be more liberal than that of the Senate's, as Democrats hold a larger majority in the lower chamber.

President Obama's position on the public option remains unclear. A Politico report Friday said that Obama prefers a "trigger option," under which a public insurer would only be created if private insurers fail to meet key pricing standards. The White House, however, says Obama hasn't taken a position either way.

The following video is from MSNBC's The Ed Show, broadcast Oct. 22, 2009.

Download video via RawReplay.com