WASHINGTON (AP) — Lawmakers returning to Capitol Hill a day ahead of President Barack Obama’s health care speech wasted no time Tuesday showing just how hard his selling job will be.

In a fresh sign of divisions in the president’s own party, a key House Democratic moderate said he can no longer support legislation that includes a new public insurance plan to compete with private industry.

And in the Senate, any hope of bipartisan agreement hung in the balance as a small group of negotiators on the pivotal Finance Committee prepared to meet in a last-ditch effort to reach consensus on a compromise bill.

Rep. Mike Ross, D-Ark., took the lead in July in negotiating changes to House Democrats’ health overhaul bill to make it more palatable to moderates.He voted for it in committee with a public plan — something most House liberals say they can’t do without.

But Ross said Tuesday that after hearing from constituents during the August recess he could not support a bill with a public plan.

“If House leadership presents a final bill that contains a government-run public option, I will oppose it,” Ross said.

The six Finance Committee senators — three Democrats and three Republicans — planned to meet to consider a new proposal that might be the last, best hope for an overhaul agreement. The proposal by the committee chairman, Sen. Max Baucus of Montana, leaves out the government-run alternative favored by liberal Democrats.

Obama, who will address Congress and the nation on health care Wednesday night, told a Labor Day audience that it’s time for insurance companies to share accountability for problems in the system.

He was not addressing the Baucus plan and it’s not clear whether he would embrace Baucus’ proposal in his speech.

Four congressional committees so far have produced partisan plans for revamping the nation’s health care system. Baucus had said he would move forward with a plan if there’s no bipartisan agreement by Sept. 15, but the chairman now faces new pressure to get a deal ahead of Obama’s speech.

Baucus would impose a fee on insurance companies to help finance coverage for uninsured Americans.

It’s not clear whether that would win support of two key Republicans in the group, Sens. Chuck Grassley of Iowa and Mike Enzi of Wyoming. The Baucus proposal reflected many of their priorities, chief among them the decision not to include the so-called public option to compete with private insurers.

Grassley said Tuesday that the administration had been “all over the ballpark” on the issue before Congress’ summer recess and that he’s still interested in finding a bipartisan consensus, if possible.

Asked on CNN about the prospect of the talks scheduled to resume later Tuesday, he replied, “We won’t know until we meet. … The good and the bad of the president speaking this week is we’ve had to speed up the work of our group to have something better … and that’s bad because we probably should have taken a little more time.”

Grassley said he was concerned that any fee charged to insurance companies would end up getting passed on to other premium holders, and he embraced the notion of nonprofit health care cooperatives to help provide coverage for the uninsured — an alternative to the public plan.

A spokesman for Enzi said the Wyoming senator remains actively involved in the negotiations, and he is reviewing the Baucus proposal to make sure it keeps a handle on costs and focuses on concerns folks brought to his attention during August.

Besides establishing a new way to purchase coverage for Americans who have trouble getting and keeping health insurance, the Baucus plan would allow Americans to keep their own doctors.

Health insurance exchanges, with information on different plans and prices, would allow small groups and individuals to buy policies at lower rates.

Medicaid would be expanded to cover more low-income people. Nonprofit cooperatives would be established as an alternative to for-profit insurance companies, giving consumers more choices. Tax credits would allow low- and middle-income Americans to buy private coverage.

The package is estimated to cost under $900 billion over 10 years.

White House press secretary Robert Gibbs, accompanying Obama on a trip to Ohio on Monday, told reporters the administration would be pleased if the Finance Committee throughout the course of the next few days would “pull together the strands of many different pieces of legislation to improve health care for all Americans.”

• Erika Werner