Rand Paul Pete Marovich/Getty Images Hours after the release of the Better Care Reconciliation Act (BCRA), the Senate Republican vehicle to repeal and replace Obamacare, four Republican senators signaled they opposed it in its current form.

Sens. Rand Paul, Ted Cruz, Mike Lee, and Ron Johnson said they will not support the current version of the bill, enough defections to prevent the legislation from passing the Senate.

"Currently, for a variety of reasons, we are not ready to vote for this bill, but we are open to negotiation and obtaining more information before it is brought to the floor," the joint statement said. "There are provisions in this draft that represent an improvement to our current health care system, but it does not appear this draft as written will accomplish the most important promise that we made to Americans: to repeal Obamacare and lower their health care costs."

"The current bill does not repeal Obamacare. It does not keep our promises to the American people," Paul said in a separate statement. "I will oppose it coming to the floor in its current form, but I remain open to negotiations."

Other Republican senators also issued tepid statements indicating they weren't ready to offer support for the bill.

One group that is skeptical is members in states that expanded the Medicaid program under the Affordable Care Act, the law better known as Obamacare. Sen. Dean Heller of Nevada, whose state expanded Medicaid and is up for reelection in 2018, said proposed cuts to Medicaid leave his support for the bill up in the air.

"At first glance, I have serious concerns about the bill’s impact on the Nevadans who depend on Medicaid," Heller said in a statement following the release. "I will read it, share it with Governor Sandoval, and continue to listen to Nevadans to determine the bill’s impact on our state. I will also post it to my website so that any Nevadans who wish to review it can do so. As I have consistently stated, if the bill is good for Nevada, I’ll vote for it and if it’s not – I won’t."

Arizona Sen. Jeff Flake, whose state also expanded Medicaid, said he had not made up his mind on the bill.

"Just got my copy of the healthcare bill and I'm going to take time to thoroughly read and review it," Flake tweeted.

Senate GOP leadership drafted the bill in closely guarded quarters over the past few weeks, and many members of the conference have not had access to the details of the plan.

A spokesperson for Sen. Susan Collins of Maine, another moderate Republicans who has expressed concern with the bill, said the senator will not pass judgment yet on the legislation.

"She has a number of concerns ans will be particularly interested in examining the forthcoming CBO analysis on the impact on insurance coverage, the effect on insurance premiums, and the changes to the Medicaid program," said the spokesperson.

Senate Majority Leader Mitch McConnell wants to vote on the bill by the end of next week.