WASHINGTON — Senate Democrats and the White House are stepping up preparations to overhaul the nation's healthcare system without the ailing Sen. Edward M. Kennedy (D-Mass.), a politically and emotionally fraught move that could dramatically alter the course of what is expected to be a titanic legislative struggle.
While battling a malignant brain tumor, the 77-year-old Kennedy -- who has devoted much of his 46-year Senate career to advocating for better healthcare -- spent months working on a sweeping bill that Democrats hope will help lay a foundation for the most ambitious health overhaul in generations.
And lawmakers in both parties were counting on Kennedy's stature and deal-making skills to help craft the kind of bipartisan compromise that many believe will be necessary if a major health bill is to pass the House and Senate.
Kennedy had planned to formally introduce his version of the healthcare overhaul shortly after Congress returned from recess this week. But he remains out of town, undergoing treatment, and is not expected back at the Capitol for at least a week or two.
Underscoring the sensitivity of the situation, Senate leaders had contemplated putting off debate on Kennedy's bill until he returned -- at the request of people close to the Massachusetts senator -- said sources familiar with the discussions who were not authorized to speak on the record.
But amid concerns from some Democratic lawmakers and the White House that the delay would jeopardize progress on healthcare legislation, Senate Majority Leader Harry Reid (D-Nev.) in the last week sought and received Kennedy's permission to move ahead without him.
Senate Democrats have set an ambitious timeline, aiming to get legislation through their chamber by August and to President Obama's desk by early fall.
Christopher J. Dodd of Connecticut -- the No. 2 Democrat on the Senate Health, Education, Labor and Pensions Committee and a close friend of Kennedy -- called committee Democrats together this week to discuss the bill.
Dodd, whom Kennedy had tapped as his chief healthcare deputy, also appeared in his place at a White House meeting Tuesday with Obama and Senate Finance Committee Chairman Max Baucus (D-Mont.), who is also developing healthcare legislation. And Tuesday night, Dodd sat down with Sen. Michael B. Enzi of Wyoming, the ranking Republican on the health committee, to talk about the legislation.
At the same time, members of Dodd's staff are becoming increasingly involved in shepherding the legislation.
Later this month, Dodd may lead a markup of the bill, a technical process in which lawmakers on the committee debate amendments. Under normal circumstance, a markup is led by the bill's author.
Speaking to reporters Wednesday, Dodd said he was not replacing Kennedy. "Sen. Kennedy is the chairman," he said, describing his own role as "coordinator of activities." Dodd also emphasized that Kennedy was continuing to speak by telephone with key lawmakers and interest groups in the healthcare debate.
But, Dodd said Thursday, Kennedy's illness has slowed development of the legislation. It now appears the Senate Finance Committee may begin considering its version of a healthcare overhaul bill before Kennedy's panel completes its work.
The Massachusetts senator's continued absence also has fed growing anxiety on Capitol Hill about his ability to lead an intense legislative campaign this summer and fall.
"I don't know of any other lawmaker who has the standing with liberal groups that he has and can work with Republicans like me," said Sen. Orrin G. Hatch (R-Utah), a longtime friend.
"If he were here, he and I would be working something out. . . . I pray for him. I hope he comes back. But he has a terrible, terrible illness."
Kennedy, whose staff has provided few details about his disease or treatment, was diagnosed last year with malignant glioma, a particularly virulent tumor.
Though one of the most liberal members of the Senate, Kennedy has developed close personal relationships with many Republican lawmakers, including Enzi and Hatch. "Sen. Kennedy has done a remarkable job of encouraging cooperation to work across the aisle," Enzi said Thursday.
At the same time, the Massachusetts lawmaker retains unrivaled credibility with liberals who are clamoring for a more government-driven solution to the nation's healthcare crisis -- an approach that is anathema to Senate Republicans.
Some on Capitol Hill believe that Kennedy's involvement could be decisive in putting together a final healthcare package.
"I'm here," Dodd said before meeting with Obama this week, "replacing someone who is irreplaceable."
Janet Hook in the Washington bureau contributed to this report.