From Greg Sargent at the Plum Line, this cheering news:

I’ve got the latest internal whip count numbers from Dem Rep. Raul Grijalva, the co-chair of the Congressional Progressional Caucus, who tells me that nearly three-fourths of House Dems will support a health care reform bill with the most robust version of the public option. That’s the one that would reimburse providers at Medicare rates plus five percent.

“I am confident that we have the support of over 70% of the Democratic Caucus,” Grivalva said in a statement emailed my way. That means according to him, around 180 of the 256 Dems in the House are prepared to back the robust public option right now.

The support in the House for the robust public option is a crucial number, and is being closely watched by reform proponents, because it will have a direct impact on the final bill. If a bill passes with a strong version of the public option, that would give House Dems more leverage when the bill is merged with the final Senate version.

Grijalva’s office disputed a recent report in The Politico citing anonymous aides claiming the robust public option only had the support of 145 Dems.

Grijalva and other progressive leaders have been counting votes at the request of House Dem leaders, who are putting together their final bill and asked liberals to show them the support they can muster for a strong public option.

To be sure, liberals still have a ways to go before securing the 218 votes needed for passage, and it’s unclear how many more votes they can pull together and whether the most robust public option will end up in the House bill. But liberals are not done whipping votes yet, and they think the public option has the momentum.

Bottom line: The stronger the support for the most robust version, the greater the pressure on the House leadership to keep a strong public option in the final bill. More later.