Congress returns to Washington next week amid mounting Republican skepticism that the party will be able to deliver on its pledge of repealing and replacing Obamacare.

"I'm not sure I'd put a bet on it," Sen. Ron Johnson of Wisconsin told me in an interview. His comments followed an interview Sen. Richard Burr gave to a North Carolina television station in which he called the House-passed health-care bill "dead on arrival," adding: "I don't see a comprehensive health-care plan this year."

A third Republican senator, speaking on condition of anonymity, told me the only health-care bill capable of passing the Senate would be a "narrow" approach repairing marketplace exchanges and preserving Obamacare's expansion of Medicaid, while perhaps loosening regulations on states and changing how the federal government shares Medicaid expenses with them. The problem with that more modest approach, the Republican senator conceded, is that the more conservative House Republican caucus might reject it.

Those individual comments are significant because Republicans have only a narrow 52-seat Senate majority. To pass a bill without help from Democrats, Majority Leader Mitch McConnell's caucus could only suffer two defectors, which would allow Vice President Mike Pence to break a 50-50 tie.

Burr's assessment of the American Health Care Act narrowly passed by the House reflects its myriad political problems. The Congressional Budget Office estimates it would result in 23 million fewer Americans with health insurance and raise costs for older and sicker people while providing a tax cut for the wealthy.

Meanwhile, insurance companies have been rattled by uncertainty over not only the long-term fate of Obamacare but also the near-term prospects for federal payments that under the 2010 law help reduce co-payments and deductibles for low-income beneficiaries. If the Trump administration withholds those payments, as it has threatened to, health insurance premiums would spike.

Facing that array of difficulties, Johnson, a conservative former private-sector CEO who won a second term last year, suggested that the Senate pause and take "short-term action to stabilize the markets" by assuring those federal payments. Then, he said, Congress could take "a thoughtful approach," perhaps involving Democrats, to "repairing the damage" he says the Affordable Care Act caused.

Such an approach would neither satisfy Republicans who have demanded outright repeal of Obamacare for years nor square with the campaign promises of President Donald Trump. There are multiple ideas in circulation — from more closely targeting the House bill's subsidies toward the old and sick, to scaling back its Medicaid cuts, to automatic enrollment in health insurance under rules states could determine.

Yet there's no consensus around any single approach at the moment, and not much time to develop one and get it onto Trump's desk. Congress has only seven weeks in session until its August recess.

That August recess represents the unofficial deadline by which Republicans have said they will either enact a health-care bill or simply move on. And what they would move on to is tax-cut legislation that Trump and GOP business supporters value more.