Updated: 4:58 p.m.

With their top priorities in the health care overhaul fading quickly in the Senate, liberal House Democrats want some face time with President Barack Obama to press him to hold the line.

Leaders of the 82-member Congressional Progressive Caucus made the request for the sit-down in a letter to Obama on Friday, but it has taken on new urgency after Sen. Joe Lieberman (ID-Conn.) signaled over the weekend he would oppose a compromise that expands Medicare.

Rep. Raúl Grijalva (D-Ariz.), co-chairman of the Progressives, said Monday that the Lieberman announcement “basically guts any issue dealing with what pretends to be a public option.—

“Anything that comes out of the Senate would be devoid of what was in the House bill and so a conference is required,— Grijalva told ABC’s “Top Line.—

The liberal group is the largest Democratic voting bloc in Congress. But the White House has maneuvered to keep liberals at arm’s length as they negotiate a health care package that can pass muster with Senate moderates. In late October, for example, with their favored version of the public insurance option on life support in the House, Progressive Caucus leaders sought a meeting with Obama to try to revive it. But the White House delayed that huddle until after House Democratic leaders had unveiled a bill with a more moderate version of the plan.

In their letter requesting the meeting, Grijalva and co-chairwoman Rep. Lynn Woolsey (D-Calif.) said they are “very concerned that the overall strength of the House bill will be damaged by proposed changes in the Senate.— They ticked off a list of items that “must— be included in a final package, including a national public option, affordability credits and insurance market reforms. But having demonstrated once that they were willing to swallow their misgivings by lining up behind House passage, the question remains what Senate compromises would constitute deal-breakers for House liberals.