President Barack Obama’s welcome home from his latest successful overseas trip is clouded by the growing doubts about his most important domestic initiative, the overhaul of the dysfunctional U.S. health care system.

On the surface, things went well for the No. 1 project on his list while he was away. Hospitals pledged to find $150 billion in savings that could be applied to expanding coverage to more of the uninsured.

The chairmen of three House committees that share jurisdiction over health care prepared to unveil a single, common proposal – a step the Clintons were never able to achieve in their effort at reform. Insurers, doctors and other key interest groups continued to negotiate with the administration, rather than launching broadsides against its plans.

But if you probe a little deeper, what you find are growing questions among the insiders – the kind of fault lines that could spread to threaten public support for the ambitious overhaul Obama has in mind and the political coalitions needed to move it through Congress.

Veterans of previous health care battles I interviewed this past week are still mainly of the view that Obama can succeed. Dissatisfaction with the status quo pervades much of business leadership, the ranks of state government and millions of households. Obama is widely praised among the insiders for staying flexible and keeping himself available to negotiate the needed compromises.

But on several fronts, forces have been moving against him, leaving even some of his allies uncertain whether he will prevail.

The staggering economy and the continued uncertainty about the timing and strength of a recovery have sapped public confidence in Washington’s ability to pull off big ventures. Growing talk that unemployment may top 10 percent and require another stimulus bill could complicate the task of finding a trillion dollars over the next 10 years to finance expanded health care coverage to the millions of uninsured.

Increasingly, Republicans on Capitol Hill and even some Democrats are voicing doubts about adding to the already enormous budget deficits. Obama has long insisted that his reform can be paid for without increasing the debt, but as the legislative process has unfolded, the question of where the offsetting savings will come from has become more urgent.

Democratic Sen. Ron Wyden of Oregon, the co-author of the one bipartisan bill already scored as saving money, told me, “As you look at what is being proposed (in two Senate committees) you don’t see savings in the 10-year budget. That’s why the discussion has shifted to finding new money to finance expanded coverage. But at home, when you tell people we’re already spending $2.5 trillion a year on health care and now we’re going to spend $1 trillion more, it just doesn’t add up.”

The realization is spreading in Congress that to achieve significant cost controls, a fundamental restructuring of health care delivery will be needed. But Rep. Jim Cooper of Tennessee, a veteran of the failed Clinton effort and the leader of conservative “Blue Dog” Democrats on health reform, told me that the proposals under discussion “are weak on delivery system reform.”

Obama, he said, clearly gets the need for drastic change. The president has been citing the June 1 New Yorker article by Dr. Atul Gawande pointing out the extraordinary differences in the cost of health care between El Paso and McAllen, Texas. El Paso has reorganized its medical services into cooperative networks of practitioners, delivering quality care at low cost. McAllen, like most American cities, relies on an unstructured collection of individual physicians and hospitals, competing for business and raking in as much money as they can.

Many others who have worked in the system argue similar points, and some of them have begun to suggest that before attempting to reorganize the whole health care system, Congress should rationalize Medicare, where costs are soaring in McAllen-like fashion.

But Congress shows no sign of having the will or the skill to challenge the myriad, well-entrenched and influential players in the current delivery system. Unless he can prod it to act differently, Obama may find himself signing a bill that condemns us to continued medical inflation.