You’d think that the GOP would be speeding through a structured dismantling of the health law they’ve been maligning for the better part of a decade given the party’s control of the House, the Senate, and the White House. But Republicans are decidedly split on how to proceed as President Donald Trump is slated to give his first-ever address to a joint session of Congress Tuesday night.

Congressional leaders including Senate Majority Leader Mitch McConnell and House Speaker Paul Ryan reportedly want Trump to offer more details on health care policy and an Obamacare replacement strategy in his speech, according to CNN. Specifically, they want him to come out and endorse the House’s recently-leaked Obamacare replacement blueprint.

It’s not hard to see why. On Monday, two powerful conservative leaders in the House declared the blueprint unacceptable because it relies on giving people refundable tax credits to purchase insurance – a policy mechanism that, in a very rough sense, resembles Obamacare’s subsidies to buy mandated health coverage (and is therefore being slammed by conservatives as just another entitlement program).

“There are serious problems with what appears to be our current path to repeal and replace Obamacare,” said Rep. Mark Walker of North Carolina, who leads an influential 170-member bloc of conservative lawmakers called the Republican Study Committee, adding that he could not “in good conscience” vote for such policies. Freedom Caucus Chairman Rep. Mark Meadows said he’d also oppose the plan.

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The ideological tug-of-war between the GOP’s various factions highlights why former House Speaker John Boehner recently said that a wide-ranging repeal-and-replace is “not what’s going to happen.”

“In the 25 years that I served in the United States Congress, Republicans never, ever one time agreed on what a healthcare proposal should look like. Not once,” said Boehner during a health care conference in Florida.

But House leadership tried to quash the intra-party tension narrative in a slew of statements Tuesday. “[The blueprint is] no longer even a viable draft that we’re working off of,” said Majority Whip Steve Scalise, the House’s number three Republican. “I feel at the end of the day when we get everything done and right, we’re going to be unified on this,” Speaker Paul Ryan asserted during a Tuesday press conference.

The implication is that (not-so) small quibbles over measures such as the tax credits won’t ultimately derail the overall repeal-and-replace strategy. After all, the blueprint contains a host of policies long sought by conservatives, including nixing Obamacare’s Medicaid expansion, an expansion of health savings accounts that individuals can contribute to, rolling back the health law’s various mandates and taxes, and dismantling the essential health benefits package that insurers had to provide under Obamacare.

But there are still many open questions about what effect such changes will have on insurance markets and Americans’ health care costs. For instance, it’s unclear how preserving guaranteed insurance eligibility for people with pre-existing medical conditions can work without the unpopular coverage mandate (since people could then just buy insurance when they get sick, bankrupting insurers), or how governments would fund historically pricey “high-risk pools” for the sickest Americans. Depending on the final policy ingredient list, the individual insurance market could actually become even more expensive and tumultuous, including in the regions where Obamacare was actually working well.

Then there’s the issue of what Trump himself wants. Health and Human Services Secretary Tom Price has told Congressional leaders that the White House is largely on board with the House GOP’s blueprint. But Trump has presented a scattershot list of ideas when it comes to health care. He’s endorsed policies like direct drug price negotiation in Medicare (usually a Democratic wish list item that’s despised by drug makers) while simultaneously promising to slash other regulations on the biopharma industry; he famously promised “insurance for everybody” yet ostensibly supports benefit cuts and a rollback of the Medicaid expansion, which has covered millions of the poorest Americans. Just how much detail Trump will present in tonight’s speech – or whether he’ll stick to a more vague “rally around the leader” approach to galvanize the legislative troops – is unclear.

In a meeting with major health insurance company CEOs Monday, the president employed his well-known penchant for bombast, promising a “fantastic” replacement plan that the industry would love. “A very competitive plan, costs will come down, health care will go up very substantially. People will like it a lot,” he said while slamming Obamacare’s affect on health care.

It’s one thing to make those aspirational claims. But the actual policy details will determine their viability. We’ll find out soon enough if we’re getting some tonight.