More than 80 conservatives have outlined their wishlist for a Senate healthcare bill in order for the plan to earn their support.

"As the Senate considers new options to replace Obamacare, it is critical that any bill includes solutions that give consumers more choice, create real flexibility for Medicaid, bring more free market principles into the market, and rein in long-term growth of Medicaid," the conservatives, who are part of the Conservative Action Project, wrote in a memo released Tuesday.

The memo's signatories include former Attorney General Ed Meese, Heritage Action for America CEO Mike Needham, and Tea Party Patriots President Jenny Beth Martin.

To earn their support, the memo states the Senate's healthcare bill must address four principles: consumer choice, Medicaid flexibility, market reforms, and reining in long-term Medicaid growth.

The group urges the Senate to allow insurance companies that sell at least one Obamacare-compliant plan to sell others that do not comply with Obamacare's insurance regulations, and calls on lawmakers to allow consumers to buy insurance across state lines, expand association health plans, and let consumers use Health Savings Accounts to pay for premiums.

"Either get the ‘replace' program right or fulfill the promise to repeal Obamacare now and take more time replacing it," the memo states. "It's more important we get it right than get it fast."

Senate Majority Leader Mitch McConnell, R-Ky., has struggled to gain consensus on a plan revealed late last month that repeals and replaces part of Obamacare.

Conservative and moderate Republicans both came out in opposition to the bill, though for different reasons.

Faced with growing opposition, McConnell delayed a vote on the proposal.

If Republicans can't coalesce around a healthcare bill, some conservative senators are pushing for a two-step approach to Obamacare's repeal and replacement, with a vote on Obamacare's repeal occurring first and a replacement plan coming later.

The repeal-first-replace-later strategy has gained traction among President Trump and Vice President Mike Pence, as well as the conservative leaders who signed the memo Tuesday.

"If Congress cannot get the replacement plan right, it should simply repeal Obamacare effective December 31, 2018, and take the time needed to get the new solution right," the memo said. "It must be a full and complete repeal of all the tax increases, all the spending, and all the regulations. Don't try a partial repeal in which Republicans keep some of the tax increase, or some of the spending, or some of the regulations."

Moderates, meanwhile, are leaning toward working with Democrats on a healthcare proposal, and McConnell said last week Republicans may have to work across the aisle to stabilize the health insurance markets if they can't all get behind one bill.