WASHINGTON — In kicking his top priorities to Congress, President Donald Trump is setting the stage, intentionally or not, for weeks of messy horse-trading that may culminate in a year-end standoff to avoid another government shutdown.

Trump is betting he can pressure Congress into breaking its gridlock and squeeze some concessions from Democrats.

But his own flip-flops on key issues have left lawmakers unable to trust the White House’s leadership and uncertain how to resolve the most thorny policy disputes.

The latest example came Wednesday when Trump reversed course again, criticizing a short-term fix to the Affordable Care Act that he had endorsed just a day earlier. That sent lawmakers back to negotiating.

“This president keeps zigging and zagging, so it’s impossible to govern,” said Senate Minority Leader Chuck Schumer, D-N.Y.

The chaos could become a liability if it distracts Congress from making progress on its tax reform package or undercuts Republicans’ leverage with Democrats on issues such as helping participants in the Deferred Action for Childhood Arrivals program, stabilizing the Affordable Care Act and funding the government.

The seeming lack of a clear strategy has complicated the fall agenda for Congress. Republicans, who control the House and Senate, would rather focus their remaining time this year on advancing Trump’s tax cuts package, which faces its own problems amid intraparty disputes. Instead, they are now facing a series of deadlines on difficult issues: immigration, health care, the Iran nuclear non-proliferation deal.

The result of Trump’s outsourcing may be to push Republicans and Democrats to an agreement by Dec. 8, if not sooner, when they face a series of must-pass votes, including one to fund the government and extend the nation’s debt limit. If Republicans are unable to pass those measures on their own, as has been the case in recent years, that could provide Democrats with a vehicle to push their own priorities.

Sen. Lamar Alexander, R-Tenn., chairman of the Senate Health Committee, predicted Wednesday that the bipartisan fix to the Affordable Care Act, also known as Obamacare, that he negotiated with the panel’s top Democrat, Sen. Patty Murray of Washington, could still be approved.

Alexander said he and Murray would formally unveil the bill Thursday.

“My guess is that it will be a part of discussions,” between the president and congressional leaders, Alexander said after talking with Trump.

Trump on Tuesday called the health care compromise a “good solution” that would bring down health care premiums. But after conservatives balked, Trump on Wednesday backed away, calling it a “bailout” for the insurance industry and demanding more concessions from Democrats.

Delaying action and piling up too many items on the to-do list at year end is not without risk.

On immigration, young immigrants in the DACA program face deportation if Congress fails to meet Trump’s demand for a new strategy. In September, Trump announced an end to the Obama-era program that offers those who were brought to the U.S. illegally as children to obtain temporary permits to work and remain in the country.

Trump first said he wanted to help DACA participants stay in the U.S. But after criticism from anti-immigration voices in the GOP, Trump sent Congress a long list of demands that even some Republicans would not be willing to accept.

“The president’s pointing fingers,” said Schumer, who helped negotiate the DACA deal with Trump. “He blames Mitch McConnell for obstruction, he blames the Democrats for obstruction. He’s the obstructionist in chief because he can’t stick to a position.”

Eventually Congress will be forced to deliver. Republicans, in particular, are worried about facing voters next year having little to show for their hold on the White House. But they are also loath to make compromises on health care or immigration that could anger Republican voters already upset at inaction on Trump’s many campaign promises.

House Speaker Paul Ryan, for one, is opposed to the Alexander-Murray deal. “The speaker does not see anything that changes his view that the Senate should keep its focus on repeal and replace of Obamacare,” said spokesman Doug Andres.

Trump could step in and lead the way, as presidents often do, or he could remain on the sidelines as Congress tries to broker outcomes on its own.

Both seem unlikely. Congress has shown it is often unable to deliver without presidential leadership and Trump, who promised to disrupt Washington, is unlikely to change his free-wheeling, unpredictable style.

lisa.mascaro@latimes.com