The odds for Senate Republicans to repeal and replace Obamacare got steeper over their week-long break, as opponents of their current plan dug in deeper and a path to consensus failed to materialize.

Upward of a dozen Republicans oppose the bill drafted by Senate Majority Leader Mitch McConnell. Senate leaders and the White House are still bent on pushing the legislation through in the next few weeks, but their success increasingly depends on the GOP holdouts making unlikely and unimaginable reversals on the deeply unpopular bill.

The Republican plan, as currently written, is projected to lead to 22 million fewer Americans having health insurance, a $772 billion cut to Medicaid, and 15 million fewer people enrolled in that program versus Obamacare, according to estimates from the Congressional Budget Office.

While members of Congress were back in their districts for the July 4 recess, opponents of the bill like Sen. Susan Collins (R-ME) became even more brash in their intransigence. At the same time, usually reliable Republican votes like Sen. John Hoeven (R-ND) came out against the plan.

McConnell’s best hope now is cosmetic changes to the legislation that, while not changing the underlying structure, could give opponents cover to come around and support it. But after their past comments on the bill, it’s hard to imagine how some of these holdouts could ever support anything resembling the current plan. That would require epic reversals over relatively modest policy changes.

Given the thin margin for error — 50 of the 52 Senate Republicans must back the health care bill — it’s become increasingly difficult for it to pass. But McConnell and his lieutenants are going to try. They want to be done with health care before August.

Leadership can still make some tweaks to the bill

Senate leaders are going to make changes to the existing bill. Sen. John Cornyn (R-TX) even made the patently ridiculous claim on Friday that the Senate hadn’t produced a bill yet.

As we seek to save Americans from failures of Obamacare, reports of polls fail to acknowledge that no Senate bill yet exists #workingonit — JohnCornyn (@JohnCornyn) July 8, 2017

They’ll likely tweak the existing plan and try to sell it as a brand new product.

One amendment known to be under consideration has been advanced by Sen. Ted Cruz (R-TX), one of the conservatives opposed to the current bill because it doesn’t roll back Obamacare’s insurance regulations enough.

The Cruz proposal would allow health insurers to sell non-Obamacare plans as long as they also sold plans that compiled with the law’s regulations. Conservatives think this would help lower premiums, while also allowing Republicans to claim that they are maintaining Obamacare’s popular protections for people with preexisting conditions.

McConnell sent the amendment to CBO for analysis last week. He has also charged Cruz with selling his colleagues on the plan, the Washington Post reported, many of whom are skittish about rolling back the Obamacare regulations most favored by the public.

The thinking goes that if conservatives get a win on regulations, they would be amenable to keeping some of Obamacare’s taxes on the wealthy. That could in turn give McConnell more money to spend on financial assistance for Americans to purchase private insurance and perhaps on softening the current plan’s deep Medicaid cuts. That might assuage some moderate concerns.

But it’s not at all clear that those changes would do much to change the bill’s bottom line from CBO: a dramatic increase in the uninsured compared with Obamacare.

Moderate senators have dug in against the plan’s coverage losses and Medicaid cuts

Further complicating matters for McConnell is the comments moderate senators have made in opposing the current bill. Those public statements will make it very difficult for any of these members to reverse course and support even a revised version of the bill.

"I cannot support a bill that is going to result in tens of millions of people losing their health insurance,” Collins said late last month, per the Washington Examiner.

The current bill is expected to lead to 22 million more uninsured Americans. It seems unlikely McConnell can dramatically improve that number with the changes now under consideration.

Another prominent holdout, Sen. Lisa Murkowski (R-AK), suggested to me a few weeks ago that she couldn’t support any bill that ends the generous federal funding for Obamacare’s Medicaid expansion, as the current bill does. Some moderate senators pushed for a more gradual phaseout of that funding, but the result is the same.

“I want greater access and lower costs,” Murkowski told me. “For instance, if you are going to eliminate Medicaid expansion or even if you're going to wind down Medicaid expansion, that's not increasing access.”

A third moderate opponent of the bill, Sen. Dean Heller (R-NV), is also preoccupied with Medicaid. He held a press conference with his state’s overwhelmingly popular Republican governor, Brian Sandoval, who has harshly criticized the current Senate plan.

“This is all about Medicaid expansion,” Heller said, adding: “It’s going to be very difficult to get me to a yes.”

McConnell can make some changes — increased aid for private insurance, faster growth for the bill’s Medicaid spending caps, an even more delayed end to Medicaid expansion funding — in a last-ditch attempt to win over the holdouts. The moderates have left themselves an opening to come around, by noting that their opposition is to the “current” bill.

But any of these tweaks won’t change the underlying structure of the legislation. It would still end the generous Medicaid expansion funding, still cap Medicaid spending, and still likely lead to millions fewer Americans having health insurance, according to the CBO’s projections.

Senate leaders and the White House have one more trick up their sleeve, per the Washington Post: They could offer alternative estimates to the CBO’s to persuade these senators that the bill’s consequences won’t be as devastating as the budget office has projected.

But that would still require a dramatic leap of faith from the moderates — particularly from those like Collins (considering a 2018 gubernatorial bid) and Heller (facing the toughest reelection race next year) with ample political motivations to oppose the bill in any form.

Conservatives are demanding a big win on regulations before backing the bill

Those three moderate votes are enough to stop the bill. But on the other end of the ideological spectrum, a quartet of conservative senators are making themselves much more difficult to get.

Cruz, Rand Paul of Kentucky, Mike Lee of Utah, and Ron Johnson of Wisconsin all oppose the current Senate bill because it doesn’t do enough to undo Obamacare’s insurance regulations. The conservatives’ No. 1 priority is lowering premiums, and they believe deregulating the insurance market will achieve that.

McConnell is giving the Cruz amendment serious consideration, by sending it to the CBO, but he is also placing the onus on the conservatives to make the case for it.

The problem is it could simply be a nonstarter for too many other Republicans: Sen. Chuck Grassley (R-IA) said over the holiday that the amendment was “subterfuge” that would undermine the protections for people with preexisting conditions. Grassley is not a vote that Senate leaders can afford to put in jeopardy.

But if conservatives can’t get the Cruz amendment, it’s hard to imagine how they could ever back the Senate bill. Lee and Paul in particular have put themselves further and further out of reach. Lee’s office told Axios last week that he would not vote for the plan without Cruz’s proposal.

Paul, perhaps the most difficult vote to get on the conservative side, has a litany of problems with the current bill — problems that almost assuredly won’t be alleviated as McConnell makes some last-minute tweaks to the proposals.

For example, he is strongly opposed to more than $100 billion in funding in the legislation for health plans that is supposed to stabilize the insurance markets. He has derided that funding as a Republican giveaway to the insurance industry.

"If you told me I couldn't repeal everything and some of Obamacare would remain, I would vote for that as an imperfect bill," Paul told me last month. "But I'm not voting for one that has new Republican entitlement programs — like that stabilization fund they're talking about is a Republican entitlement program for a billion-dollar insurance industry."

Even Cruz, who has sought to be a dealmaker in the Senate negotiations, may feel he can’t support the bill without his amendment — especially after his ally Lee has made the proposal a condition of his support.

It adds up to what seems like an impossible task for McConnell. A critical mass of senators in the middle and on the right oppose the bill, and they are trying to pull the plan in dramatically different directions.

His best hope, it seems, is cosmetic changes to give any converts cover and the threat of failure if Republicans don’t undo Obamacare as they promised to do for seven years.

The Senate leader remarked last week that if Republicans fail to pass their own legislation, they would have to work with Democrats on a smaller bill to shore up the health care law.

It sounded like both a threat — and an admission that Republicans really might fall short.