Just days after a draft circulated of GOP plans to repeal and replace the Affordable Care Act, at least one critical Republican has publicly said he would not support the bill in its current form.

Rep. Mark Walker, R-N.C., called the draft bill "a new health insurance entitlement with a Republican stamp on it."

“There are serious problems with what appears to be our current path to repeal and replace Obamacare," Walker, head of the conservative Republican Study Committee, a 170-member group of Republicans, said. "The draft legislation, which was leaked last week, risks continuing major Obamacare entitlement expansions and delays any reforms. It kicks the can down the road in the hope that a future Congress will have the political will and fiscal discipline to reduce spending that this Congress apparently lacks. Worse still."

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Walker's vocal opposition signifies the challenges that House Republicans face in passing any bill to repeal and replace the ACA. It also draws a line in the sand, pressuring House leadership to change the bill.

Related: GOP Draft Health Care Bill Cuts Medicaid, Insurance Subsidies

Making good on promises of "repeal and replace" has proven difficult for Republicans, since members of the party are divided on what a replacement should look like and how much it should cost. Republican leaders, meanwhile, have promised not to "pull the rug" out from under people who are covered by current law after facing scores of concerned voters at town halls across the country. But they are still trying to figure out a way to provide health care to large numbers of people while reducing the costs for consumers and reducing the amount of federal funding for the program.

A 105-page draft proposal dated February 10 was leaked last week and obtained by NBC News after circulating among health care lobbyists. While changes are possible, it is believed to be a legitimate effort at health care reform.

"This is the bones of what's going to happen," said an aide to a House Republican.

The draft bill phases out the current Medicaid expansion and would implement grants for states to provide Medicaid based on population, instead of on a person's income.

It gets rid of the subsidies for health insurance based on income and replaces it with tax cuts based on age. The proposal also creates state-based high risk pools for people with pre-existing conditions or are expensive to insure, and it greatly expands the use of Health Savings Accounts.

Additionally, as Republicans struggle to figure out a way to pay for their ACA replacement, the proposed bill calls for a tax on the most expensive employer-based health insurance plans, which is an expanded version of the so-called Cadillac tax on the most expensive employer based plans.