Mr. Manchin, whose demand that the overall package not exceed $1.5 trillion has driven a frenzied effort to cut the cost of the bill, has maintained that he is keeping an open mind out of fairness to Mr. Biden and Democratic leaders.
But he has proved unyielding on many of progressives’ most cherished priorities, such as Mr. Sanders’s drive to add vision, hearing and dental benefits to Medicare.
“Bernie and I have met the last three days for at least an hour a day, getting to know each other differently than we ever did before,” Mr. Manchin said he had told Mr. Biden on Sunday. “He has my respect. I know who he is, and where he’s coming from. I just respectfully disagree.”
That resistance has not stopped Democrats from trying to sway him. These days, Mr. Manchin can usually be found huddled with colleagues who are seeking his support — or to change his mind — on a component of the social policy bill. On Monday evening, it was Senator Chuck Schumer of New York, the majority leader, along with Senators Thomas R. Carper of Delaware, Maria Cantwell of Washington, Ron Wyden of Oregon and other climate hawks seeking to salvage a fee on methane emissions and other spending to which Mr. Manchin had objected.
Where the Budget Bill Stands in Congress
A framework has yet to emerge. No final decisions have been made on the plan — which is expected to include education, child care, paid leave, anti-poverty and climate change programs — and negotiations are continuing. But even with a scaled-back version, passage of the bill is no guarantee.
Representative Richard E. Neal of Massachusetts, the chairman of the Ways and Means Committee, said he had sought a meeting with Mr. Manchin to discuss how to increase taxes to pay for the plan. He reminded reporters that the two had worked together on pension legislation.
After his breakfast with Mr. Biden and Mr. Schumer, Mr. Manchin fielded a call from Representative James E. Clyburn of South Carolina, the No. 3 House Democrat, who urged him to support a proposal to cover the cost of expanding Medicaid in states that had not done so under the Affordable Care Act. Mr. Manchin has said it would be unfair for the federal government to cover those costs for some states, when others like West Virginia have expanded their Medicaid programs and received only a 90 percent subsidy.
Democrats have good reason to court Mr. Manchin’s support. They remember how difficult it was to win his vote on the $1.9 trillion pandemic aid plan enacted this year, including his last-minute effort to slash the size of the unemployment benefits included in the measure. (While Mr. Manchin ultimately voted yes after winning the concessions he sought, the grueling negotiations led to the longest open Senate vote in modern history.)