House Republicans’ long-awaited ObamaCare replacement bill already is being met with complaints from congressional conservatives who warn the proposed legislation comes with too much cost and too much government -- signaling a tough fight ahead for GOP leaders looking to send a bill promptly to President Trump’s desk.

The legislation, released Monday evening, heads next to a pair of committees where lawmakers will start refining it.

“The American Health Care Act is a plan to drive down costs, encourage competition, and give every American access to quality, affordable health insurance,” House Speaker Paul Ryan, R-Wis., said in a statement. “It protects young adults, patients with pre-existing conditions, and provides a stable transition so that no one has the rug pulled out from under them.”

But influence-wielding conservatives are likely to seek significant changes.

On the Senate side, Kentucky’s Rand Paul told “Fox & Friends” on Tuesday morning that the proposal’s call to continue the original law’s Medicaid expansion through 2020 -- before ending additional federal aid to participating states -- is “untenable.”

While the House GOP bill would nix the so-called individual mandate to buy insurance and the accompanying penalties, Paul complained that the proposal would instead let insurers add a 30 percent premium surcharge for anyone whose insurance lapses.

Paul said that’s effectively a “mandate,” only the penalty is paid to insurance companies instead of the government.

“This is in all likelihood unconstitutional,” Paul said. “This is ObamaCare Lite. It will not pass. Conservatives are not going to take it.”

Republicans behind the new legislation reject that tag.

“It is ObamaCare gone,” House Ways and Means Committee Chairman Kevin Brady, R-Texas, told Fox News’ “Special Report with Bret Baier” in an exclusive interview.

President Trump touted the new legislation on Twitter Tuesday morning.

“Our wonderful new Healthcare Bill is now out for review and negotiation. ObamaCare is a complete and total disaster -- is imploding fast!” he wrote.

The proposal indeed includes sweeping changes, to get rid of the original legislation’s various taxes, penalties and mandates.

But the Affordable Care Act’s subsidies would be replaced by a different kind of monthly tax credit. It would preserve certain patient protections, including for those with pre-existing conditions -- while calling for an eventual transition away from the current Medicaid expansion.

The legislation reflects a balancing act, as GOP leaders try not only to deliver on their campaign promise to get rid of ObamaCare, but address concerns from the moderate wing that moving too drastically could result in significant reductions in coverage.

Several moderate GOP senators sent a letter late Monday to Senate Majority Leader Mitch McConnell, R-Ky., voicing concerns about the impact for families on Medicaid.

On the other end of the spectrum, conservatives pushed back against allowing the Medicaid expansion to continue while offering a new system of tax credits

“It creates a new entitlement program and I've already heard from some constituents upset about [it],” Rep. Louie Gohmert, R-Texas, said. “We're calling it tax credits, where we actually send people checks. I guess it's another way to do the subsidy.”

Rep. Jim Jordan, R-Ohio, told Politico: “This is ObamaCare by a different form.”

Rank-and-file Republicans are watching closely to see the price tag of the bill, which still is unknown. Further, lawmakers want to see if the bill actually brings down the cost of health care.

“I can’t believe many conservative groups are going to like this,” one House Republican said.

The legislation put out Monday evening apparently is just the beginning. Trump and a top aide to Ryan both said on Twitter Tuesday that Republicans want to tackle health care in three phases.

Trump tweeted that “getting rid of state lines” to promote competition “will be in phase 2 & 3 of health care rollout.”

Health Secretary Tom Price also talked up the proposal, calling it an “important first step” in a letter to key House Republicans.

Price later clarified, during the White House press briefing, that the second phase would include regulatory changes and the third would include additional legislation. “This is about patients,” he said.

Fox News’ Chad Pergram and Griff Jenkins contributed to this report.