Four conservative senators hoped Thursday to do what the Freedom Caucus did in the House: push a Republican healthcare bill to the right and save it from near-certain defeat.

Sens. Rand Paul, R-Ky., Ted Cruz, R-Texas, Mike Lee, R-Utah and Ron Johnson, R-Wis., announced they would not be able to vote for the recently unveiled Senate healthcare bill, which was designed to at least partially repeal and replace Obamacare, in its present form.

"Senator Paul believes that conservatives need to be included at the negotiation table," said Paul's communications director, Sergio Gor. "Staying united will be important, similar to the Freedom Caucus."

In the House, conservatives managed to establish themselves as the main faction the president dealt with in healthcare negotiations. After the first version of the American Health Care Act proved unacceptable to conservatives, they forced through another version that passed the House.

When Obamacare originally passed Congress, liberal Democrats were forced to negotiate with centrists. They discarded the public option and other liberal priorities to pass a bill that included insurance market exchanges and Medicaid expansion.

"Freedom Caucus members are still reviewing the bill but have a number of concerns that they hope to see addressed in the amendment process" said a caucus source. "Sen. Ted Cruz, in particular, has a market-based consumer choice measure he's been working on that would garner broad support from the group."

"This is basically an amendment to Obamacare, not repeal of it. So much for campaign promises, right?" said FreedomWorks' public policy and legislative director Jason Pye. "I recall [Senate Majority Leader] Mitch McConnell saying he would repeal ObamaCare 'root and branch.' Yeah, this bill doesn't do that. We hope that Sens. Lee, Cruz, and Paul can guide the bill in a direction that lowers health insurance premiums."

Paul, who represents Kentucky in the U.S. Senate alongside McConnell, said much the same thing in his own remarks.

"It's gotta look like what we promised," Paul said Thursday afternoon. "I mean we promised — I heard people, I traveled the country. I heard other Republicans say ‘we are going to rip it out root and branch' thousands of times."

But it is not going to be easy. Centrist Republicans in the House were mostly able to vote against their chamber's Obamacare replacement, the American Health Care Act, once most Freedom Caucus members voted for it.

Republicans have a 24-seat majority in the House. There is only a 52-48 Republican Senate majority in the Senate. Sens. Susan Collins, R-Maine, and Lisa Murkowski, R-Alaska, are as important as any of the conservatives. These centrists want to fix Obamacare, not necessarily replace it.

Conservatives like Cruz are hoping for changes in the opposite direction. House conservatives insisted months ago that they wanted to get to yes on the House-passed bill, and it was centrists like the Tuesday Group, as opposed to conservatives, who were making it impossible.

"Ideally, we would like to vote for a bill that repeals Obamacare, yes," said Lee's communications director Conn Carroll.

This is similar to what Freedom Caucus members said before their bill finally passed the House. "The only thing we will be judged by is ‘Do premiums come down?" Rep. Mark Meadows said in a meeting with the Washington Examiner.

The version of the bill that is being floated in the Senate jeopardizes centrist votes by allowing state-level waivers from major Obamacare coverage mandates, defunding Planned Parenthood and other well-known abortion providers and tweaking tax credits for consumers who need new health insurances.

Deleting any of these provisions carries the risk of losing conservative votes, after a number of them were won after major changes to the bill.

That hasn't stopped conservatives from either chamber of Congress from making demands.

"In general, the bill's going to have to look more like a repeal bill and less like we're keeping Obamacare" said Paul. "It has to look less like Obamacare lite."

President Trump, on the other hand, seems to be strengthening the centrists' position.

"I hope we are going to surprise you with a really good plan," he told a rally Wednesday evening. "I've been talking about a plan with heart. I said, ‘Add some money to it!'"

That's not exactly music to conservatives' ears.