President Donald Trump, the indispensable salesman for the GOP’s hopes to repeal and replace Obamacare, still can win. But he’ll have to clear hurdles in every direction.

To amass a House majority for Speaker Paul Ryan’s proposal, the White House can only lose 21 of their members on a floor vote. Trump faces two competing blocs of intra-party opposition, whose goals are in direct conflict.

On one side are 23 Republicans holding House seats in districts Hillary Clinton won last November. They want more generous benefits than the current version of the bill provides.

Some of them, including Darrell Issa of California, Peter Roskam of Illinois, and Ileana Ros-Lehtinen of Florida, have voiced reservations publicly. For this group, the Congressional Budget Office analysis projecting that 24 million fewer Americans will have health insurance by 2026 has created intensifying political pressure.

On the other side is a larger group of staunch conservatives who complain that Ryan’s bill is too generous, with tax credits that create a new entitlement program amounting to what they call “Obamacare-lite.” Leaders of the House Freedom Caucus, such as Mark Meadows of North Carolina and Jim Jordan of Ohio, have expressed sharp criticism.

Either group, by voting as a bloc, could sink the health-care bill.

In the Senate, Trump needs to hold 50 of 52 Republicans. That would allow Vice President Mike Pence to break a tie in the administration’s favor.

There, he faces similar dynamics as in the House. Some of the most ideological Senate conservatives, such as Mike Lee of Utah and Rand Paul of Kentucky, have blasted the House bill as enshrining big government.

At the same time, senators representing states where Obamacare has extended coverage to large numbers of low-income whites have also expressed reservations about insurance losses under the House bill. They include Tom Cotton of Arkansas, Shelley Moore Capito of West Virginia, Rob Portman of Ohio, and Susan Collins of Maine.

Trump holds one powerful advantage in the attempt to overcome those divisions. Party unity in Congress has strengthened dramatically in recent years. The president remains highly popular among rank-and-file Republican voters who for years have rallied behind promises from party leaders to repeal Obamacare. If the president and GOP leaders make an urgent case that enacting the House bill is vital to preserving Republican majorities in 2018 and beyond, history suggests they have decent chances of whipping House and Senate majorities in line.

Yet that strategy depends on unity at both ends of Pennsylvania Avenue. Glimmers of doubt about that unity have started to emerge.

The White House has resisted identifying the House proposal as “Trumpcare,” preserving narrow but unmistakeable distance from Ryan., the website formerly run by chief White House strategist Steve Bannon, calls it “Ryancare” in critical articles. The site also reminded readers this week of Ryan’s announcement to colleagues last fall that he would no longer defend candidate Trump against Democratic attacks.

A different warning has also emerged in conservative media: Health care could become a political quagmire, siphoning energy from more promising endeavors such as tax reform to boost economic growth.

The health-care debate “has become mind-numbingly complicated,” wrote the influential commentator Byron York in the Washington Examiner. “And perhaps the answer to all those questions is one simple sentence: Republicans are working on the wrong thing.”

If the president disagrees, he will need to make that emphatically clear — and soon. As in the March Madness basketball tournament that begins this week, chances for Republican victory on health care depend on the coach calling the play and the players following his lead.