President Trump speaks during a meeting with members of the House Ways and Means Committee as committee chairman Rep. Kevin Brady (R-Tex.) listens on Tuesday, at the Roosevelt Room of the White House, to discuss the Republicans’ plan for tax reform. (Alex Wong/Getty Images)

Republicans have admitted defeat (for now) in their seven-year war to repeal the Affordable Care Act. House and Senate Republicans could exploit budget rules to take another stab at repeal later this year or next. But for now, Republicans seem poised to move on to taxes.

Many think that tax reform will be easier for Republicans than health care. True, taxes offer much more familiar ground for Republicans. But these four key causes of GOP failure on health care could infect their tax campaign as well.

1. Congressional Republicans still have a small, overreaching majority

For seven years, Republicans promised a wholesale repeal of Obamacare. Unexpectedly in control of Congress and the White House — and facing Democrats who have no interest in repealing Obama’s signature achievement — a slim Republican majority this year overreached.

This is not the first small majority to overestimate its power: George W. Bush and his Republican majorities in 2001 and 2005 also pursued an aggressive agenda that catered to a conservative base. They cut taxes, but failed to deliver education vouchers, faith-based initiatives, and privatization of social security, to name a few top priorities.

Senate Republicans seem poised to overreach again on taxes, especially given opinion surveys that register little public support for cutting corporate and other taxes. House and Senate Republicans disagree with each other and among themselves on the key parameters of a tax deal — including the size and scope of cuts, whether or how to pay for them, and how fast and loose to play with budget rules for estimating costs. The political urge to get something done before they face voters in 2018 may yet compel compromise. But it’s just as likely that in overreaching, this small majority will end up tied in knots.

2. Reconciliation remains a double-edged sword

Republicans seem intent on legislating by simple majority, avoiding the need to court Democratic votes. To do so, House and Senate GOP must first agree on a budget blueprint. This is the necessary first step to unlock “reconciliation”— the same type of filibuster-proof bill Republicans deployed to try to repeal Obamacare. But bicameral agreement on a budget is not yet in hand. Some members of the conservative House Freedom Caucus have even refused to back a budget without first seeing the details of the tax bill. That puts the cart before the horse, and no one has yet built the cart.

Even with a budget in hand, budget laws will again limit Republicans’ degrees of freedom in crafting a tax bill. If they can’t agree on how to pay for the tax cuts, the rules for scoring costs must be stretched far beyond the norm. Otherwise, to comply with the requirement that reconciliation bills not add to deficits in the long term, Republicans will have to settle for temporary tax cuts — undercutting the value of lowering corporate taxes in the first place.

3. It’s still irregular order

After helping to block the GOP health-care bill, Sen. John McCain (R-Ariz.) signaled that he would again demand “regular order” on taxes. Senators disagree about the meaning of regular order (if it means anything at all). But most have in mind some outdated notion of a more collegial Senate — a body in which senators incubate policy in committee, and bipartisan coalitions amend and adopt measures on the floor.

For now, congressional leaders seem committed to their irregular ways. First, the bill has thus far been devised by a cabal of congressional and White House leaders, keeping rank-and-file GOP members somewhat in the dark. Second, even if and when bill-writing is turned over to the committees, use of reconciliation precludes regular order: Senators have no incentive to pursue bipartisan solutions, since the other party’s votes are not needed.

Moreover, with the spotlight harshly focused on Republicans, the majority will lose its ability to blame Democrats for any legislative impasse. Instead, one could imagine House and Senate leaders deciding again to go behind closed doors in the search for a deal, should Republican cleavages threaten to force a tax deal off the rails.

4. Trump is still the president.

A deeply divided party needs a way to resolve differences within their ranks. Unfortunately for Republicans, a distracted and undisciplined President Trump has so far been unable to take the lead on legislative matters. Even this week, with a final push for health care and a promised rollout of the framework for a tax bill, Trump commandeered the agenda by going to war against African American athletes and the NFL. Republicans can hardly count on this president to pave the way forward when legislative differences arise.

Unified party control rarely lasts long in American politics. The window is closing for the president and Republicans to fulfill promises to their base and prove to the electorate that they can be trusted to govern. For a divided GOP, the stakes couldn’t be higher.