PHILADELPHIA — Congressional Republicans leave their annual policy retreat divided over paying for President Donald Trump’s border wall, one of several thorny issues looming to trip them up as the GOP adjusts to full control of Washington.

Lawmakers welcomed a speech from Trump endorsing their goals on repealing and replacing former President Barack Obama’s health care law and overhauling the loophole-ridden tax code. But the president’s comments on paying for the wall, and subsequent clarification and walk-backs from the White House, sowed widespread confusion Thursday.

After the White House press secretary announced a 20 percent border tax on imports from Mexico, House Republicans felt certain the administration was describing a central plank of their own tax plan — so-called border adjustment that taxes imports instead of exports. They argued it would more than pay for the wall and would end up with Mexico footing the bill in the end, as promised. But Senate Republicans, who are not sold on the House GOP tax plan, began to raise questions.

Then the White House began to walk the idea back, saying it was simply part of a menu of options.

“Many unanswered questions about proposed ‘border adjustment’ tax,” the No. 2 Senate Republican, John Cornyn of Texas, said over Twitter. GOP Sen. Lindsey Graham of South Carolina said that “any policy proposal which drives up costs of Corona, tequila or margaritas is a big-time bad idea.”

The confusion underscored the tricky currents ahead as the GOP aims to repeal and begin to replace “Obamacare” by March and complete action on taxes by summer’s end — all while paying for the border wall and other spending proposals, writing an infrastructure bill and taking must-do action to raise the government’s borrowing limit.

“It’s obvious we have an awful lot of work to be done,” said Sen. Susan Collins, R-Maine. “There’s not necessarily consensus on it, but there is a sense of excitement about it.”