WASHINGTON — The highly anticipated Senate health care bill revision released Thursday is already being met with skepticism, and even outright opposition, by some key Republican senators.

The new version is the latest chapter in a long, arduous process for GOP leaders attempting to keep a seven-year long campaign promise to repeal and replace the Affordable Care Act. It has evolved into a partial repeal of some of the Obamacare taxes as well as an effort to reform an expensive entitlement program for low-income, elderly and disabled Americans, but still keeps in place much of Obamacare's structure.

The changes in the bill were put forward to address concerns of both moderate and conservative Republicans, including a last-minute conservative addition from Sen. Ted Cruz, R-Texas, to allow individuals to purchase cheaper, skimpier health plans. It also keeps some of the Obamacare taxes on the wealthy as an enticement for moderate votes.

But even with those changes, some GOP senators emerged from a nearly hour-long briefing on the contents of the plan still expressing deep reservations. Two senators on opposite ends of the Republican ideological spectrum — Susan Collins, R-Maine, and Rand Paul, R-Ky. — have already said they are opposed to the bill and will vote against a motion to proceed, the necessary vote for the measure to be brought before the Senate. If Republicans lose any more votes, the bill will languish for a second time.

Even Sen. Mike Lee, R-Utah, who worked with Cruz on the beginning stages of his measure, said through his spokesman Conn Carroll that he's undecided on the new bill.

Sen. Paul has repeatedly called the Senate plan "Obamacare-lite."

It was released as GOP members huddled in a closed-door meeting to discuss the details of a measure that has been debated ever since Senate Majority Leader Mitch McConnell postponed a vote on the original version two weeks ago due to a lack of support. With no Democrats expected to vote for anything that overturns Obamacare, McConnell needs 50 of the 52 GOP senators to pass the bill.

Related: Here Are the Major Changes in the GOP Senate Health Care Bill

While large cuts to Medicaid will remain in place, new carve-outs have been created to protect certain populations if states choose to do so. It remains to be seen whether that will be enough to appease moderate members concerned about the size of the cuts.

"I'm still deeply concerned about the Medicaid cuts that have been included," Collins said. "They have been modified in some ways, but there's no doubt in my mind there are hundreds of billions of dollars in cuts that would ship costs onto the state governments. It would hurt the most vulnerable citizens, it would have an adverse impact particularly on our rural health care providers, hospitals [and] nursing homes."

"At this point, unless I learn something new, I am a 'no' on motion to proceed," Collins added.

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"I don't think the federal government should be subsidizing insurance companies," said Sen. Paul. "They're very successful — $15 billion a year in profit. I don't think we need a superfund for insurance companies."

A host of other senators left the meeting undecided, especially those concerned about cuts to Medicaid.

Sen. Dean Heller, R-Nev., who came out strongly against the first version of the bill said when asked if he was undecided on the bill, "At this point, yes."

Sen. Rob Portman, R-Ohio, said, "We'll see."

"I’m the same position as I’ve been in — looking at the language and looking forward to the analysis," he added.

Over the next several days, McConnell will be working to ensure the support of the rest of his conference. He held an additional meeting with a group of senators concerned about the bill's cuts to Medicaid, including Portman and Heller.

Sen. Shelley Moore Capito, R-W.V., also attended the meeting. When asked if she'd support changing how the bill deals with Medicaid in the amendment process after the bill goes to the floor, she said, "I'm going to hold comment on that. I need to really look at it."

Other details were made to gain votes from both sides of the GOP spectrum.

Here is how the bill changes to appease moderates:

A $45 billion fund to help people with opioid addiction.

An extension of three Affordable Care Act taxes: the 3.8 percent tax on investments by the wealthy; a 0.9 percent Medicare surtax for the wealthy; and a tax on insurance executive's compensation.

$70 billion to states to help stabilize the cost of health care, subsidize the cost of care for lower-income people and allow states to implement new reforms..

Here is how the bill changes to appease conservatives:

Health Savings Accounts, which are accrued from pre-tax dollars, can be used to pay for health insurance premiums.

Catastrophic health plans would be offered and people could be eligible for tax credits to help pay for them.

A health plan with narrow coverage but cheaper premiums would be offered for people in the individual market.

McConnell hopes to hold a vote on the measure next week, but first a non-partisan Congressional Budget Office analysis of how much the bill would cost and how many people would lose insurance must be released. That report is expected Monday, but may not include analysis of the Cruz amendment, according to GOP senators. Instead they could rely on an analysis from the Department of Health and Human Services and the Office of Management and Budget for that portion.

Democrats are still slamming the revised bill, saying that it creates "junk" insurance plans and "takes a hammer to Medicaid."

"Republicans are going to try to tell the American people that this bill is no longer a tax giveaway to the wealthy and special interests," said Senate Minority Leader Chuck Schumer. "Unfortunately, that just isn’t true. This bill still cuts taxes on pharmaceutical companies. It still cuts taxes on health insurance companies. And by expanding health savings accounts, they’ve created a new tax break that goes disproportionately to the wealthy in this country."

Despite the indecision and opposition from some, several Republicans say they are more optimistic than they were about the original bill's chances because of the changes.

"I think the bill is continuing to improve," said Sen. Bob Corker, R-Tenn., who wanted to see an extension on the taxes on the wealthy.

Sen. John Thune, R-S.D., emerged from the meeting optimistic. "The presentations that have been made about the changes from the last bill are going over pretty well," he said.

In the meeting, McConnell urged members to vote for the motion to proceed, arguing that they should allow them to begin debate on the bill where they'll have the opportunity to offer amendments and change the legislation.

But that argument isn't enough for Collins.

"I think we can pass a better bill. I really believe that," she said. "I don't see this as the end if this bill were not to pass. I see it as the beginning of the kind of process I would have liked to have seen in the first place."

CORRECTION (July 13, 2017, 2:25 p.m.): An earlier version of this article referred incorrectly to a surtax on the wealthy that is kept in the new bill. The surtax is in addition to the existing tax for Medicare, not Medicaid.