President Trump is more than his own worst enemy. The damage he has inflicted during his first five months in office has undermined Republican congressional leaders, frustrated members of his Cabinet, exasperated top advisers and strained relations with some of the nation’s most important allies. This week’s case study is health care.

The most significant domestic initiative of the Trump presidency and the Republican Party is the fulfillment of a promise to “repeal and replace” the Affordable Care Act. That Republicans are struggling to find an alternative to Obamacare is plain to see. But as congressional leaders scratch to find the votes to pass a bill in the Senate, the president has demonstrated that he is an unreliable partner in the battle.

On Friday morning, as Senate Majority Leader Mitch McConnell (R-Ky.) was trying to balance potentially irreconcilable demands of hard-line conservatives and more moderate conservatives, the president decided to offer his own solution with a tweet: If the Senate can’t get there, why not just repeal now and replace sometime in the future?

Never mind that earlier in the year, he took the opposite position. At that time, McConnell and some others preferred to move with an immediate repeal vote that included a trigger for implementation sometime in the future, giving elected officials the ability to say they kept a promise and enough time to try to find a replacement. But the president overrode that idea, demanding that replacement had to accompany repeal.

Now, at the worst possible moment, Trump seemed to have shifted again, leaving Senate lawmakers frustrated and baffled.

Senate Majority Leader Mitch McConnell (R-Ky.) speaks with reporters after Senate Republicans had a meeting with President Trump in Washington on Tuesday. (Jabin Botsford/The Washington Post)

The idea of going to repeal now, replace later was not originally the president’s. His tweet came minutes after Sen. Ben Sasse (R-Neb.) made a similar statement on “Fox and Friends.” Sen. Rand Paul (R-Ky.), a holdout, has been saying the same thing.

The president appears to have no commitment to an explicit strategy for getting a health-care bill to his desk, only a desire for victory and limited patience for the legislative process. He also has no fixed views on the substance of health-care reform, having made contradictory statements about the topic throughout his campaign and since.

He has said he wants a health-care system with heart, one in which everyone is covered. But he embraces legislation that would leave 22 to 23 million additional Americans without coverage by 2026, according to the Congressional Budget Office. When the House passed its health-care bill in May, he showered it and GOP leaders with praise. Later he called the measure “mean.” He campaigned against cuts in entitlements — Medicare, Social Security and Medicaid. The congressional legislation would revamp Medicaid, significantly slowing the growth in spending.

[Republicans head home for July 4 recess nervous about health care]

Presidential leadership on these big domestic initiatives generally requires a combination of two things. The president is expected to act as the leading salesperson, making the public case while legislators make the sausage. Behind the scenes, a president works to bring along the last wavering lawmakers, calling, cajoling and applying the pressure. Sometimes it doesn’t work, but those responsibilities are part of the job description of the presidency.

Former president Barack Obama spent months publicly advocating in favor of the Affordable Care Act and the value of expanded coverage and trying to slow the growth of medical inflation. Despite his limited enthusiasm for interacting with Congress, he also spent hours in private conversations with legislators, including some Republicans. He never won GOP support, nor was his measure publicly popular while he was in office, but not for lack of effort.

Through the first five months of his presidency, Trump has yet to deliver a single comprehensive speech on the topic or subjected himself to extensive questioning from reporters that would give him a forum to make his case. Nor is there evidence that the president has proven effective with many individual lawmakers.

(Jenny Starrs/The Washington Post)

Trump’s business record suggests he is an enthusiastic salesman. But the kind of hyperbole that sometimes goes with real estate deals doesn’t work so well in government. Making the public case and persuading reluctant lawmakers requires a familiarity with the subject matter that he has yet to demonstrate. What is the affirmative case he makes for the replacement now under consideration?

Trump’s most-repeated argument is that Obamacare is imploding. It is correct that there are problems of coverage in some places, as reports of insurers pulling out of some markets attest, and that premiums have risen. Republicans blame it on the flaws of Obamacare; Democrats say the uncertainty created by the ongoing debate makes insurers unwilling to place risky bets on the profitability of offering coverage.

[GOP weighs difficult trade-offs in health-care debate]

The Congressional Budget Office analysis of the Senate bill released last week offered a portrait of the current system that is less apocalyptic than the president’s rhetoric. The CBO report stated that, in part because of the individual mandate under Obamacare, the demand for insurance will continue to be strong enough “for the market to be stable in most areas.”

CBO said the Senate bill as it stood at the beginning of last week also would result in generally stable individual marketplaces. The report cautioned, however, that because of unanswered questions surrounding the new law, there could be some disruptions in those markets in the short term. But CBO said that markets would generally be stable until 2020, in part because the government would keep paying through then subsidies that help lower-income customers in ACA health plans afford out-of-pocket expenses.

Even after that, individual insurance markets in most of the country would be stable, the CBO said, although it noted that under either Obamacare or the Senate’s plans, some rural areas could run into trouble. Under the Senate bill, the analysis said: “The reductions in subsidies would lead fewer people to decide to purchase insurance — and markets with few purchasers are less profitable for insurers.”

The health-care discussions should be a top priority for the president, given McConnell’s desire to get to a vote as quickly as possible after the Fourth of July recess. Passage of a replacement for the Affordable Care Act would make it possible for Congress to move on to tax reform, which the president cares a lot about, and other parts of his and the GOP’s agenda.

Yet as Senate Republicans were in complex discussions to resolve their differences, the president created another needless distraction with his crude and sexist attack tweet Thursday aimed at MSNBC’s Mika Brzezinski. That tweet was not the first time Trump has denigrated women. Once again, it put Republicans in the awkward and embarrassing position of trying to turn their heads without truly walking away from the president.

The attack on Brzezinski and Joe Scarborough, co-hosts of the “Morning Joe” show, is part of an ongoing war with mainstream media that the White House is now waging on a near-daily basis. That conflict cheers the president’s base and helps keep those loyalists close to him despite his other difficulties.

[In tweet storm, Trump attacks MSNBC over ‘Morning Joe’ and calls CNN ‘garbage journalism’]

Congressional Republicans may abhor what the president said with his tweet attack on Brzezinski, but they are not ready to risk true confrontation with Trump and therefore his core supporters, whose enthusiasm they will need in the midterm elections.

The president’s suggestion to repeal now and replace later begs the larger question for Republicans. GOP lawmakers have spent years campaigning against Obamacare, and over the past months, in both houses of Congress, hours and hours of granular discussions have been held.

The problem is not one of needing more time to come up with a perfect solution. It is the question of whether Republicans are prepared to stand behind their criticisms of Obamacare and the political consequences that could come with significantly revising it.

Republican elected officials have campaigned as the party of smaller government, lower taxes and less federal spending. The result of that appears to be a health-care bill that would knock millions and millions off the coverage rolls, including many lower-income Americans now on Medicaid. To date, the outlines of that solution have found little support from the public.

McConnell will plunge ahead with a repeal-and-replace effort, despite the president’s interjection. Republicans now have a choice. Either they support that kind of package or they don’t. They can’t look to the president on this: He has provided limited help and little political cover. If anything, he’s made their task even more difficult as the past week showed.