PHILADELPHIA — At a White House meeting this week, President Donald Trump told House Speaker Paul Ryan he "liked" the Republicans' 200 day agenda that includes repealing and replacing Obamacare and overhauling the tax code. But he told Ryan something was missing.

Trump asked lawmakers to include the massive infrastructure spending project that he promised voters during the campaign.

Now it's been added to the GOP's already packed to-do list, outlined at the Republican retreat at a hotel in downtown Philadelphia. It's not clear whether it will match Trump's $1 trillion proposal for repairing the nation's crumbling roads and bridges, but infrastructure is now "front and center," according to those who heard details of the GOP plan.

"The impression I got is that the speaker recognized the importance of that to the president and that it is now part of our 200-day plan," Rep. Chris Collins, R-N.Y., a member of the House Republican leadership team, said of the infrastructure proposal. "Initially, without the president's input, that would not have been the case. But our president has been pretty clear on setting his priorities."

Republican leaders outlined a packed and ambitious agenda that is largely deferential to Trump. And it's one they hope Congress can complete in the coming months. It includes getting a comprehensive tax reform bill on Trump's desk by August and the repeal and replacement of Obamacare by March.

And there is much more.

Trump has also added to the GOP to-do list a special spending bill to pay for the long-promised wall on the Mexican border, which Collins said could have a price tag of "eight to ten billion" dollars.

Republican leaders outlined the agenda to rank-and-file lawmakers at the GOP retreat in downtown Philadelphia on Wednesday. Trump, who will address lawmakers on Thursday, was back at the White House, signing an executive order to start building the wall.

"They put up a chart," Rep. Charlie Dent, R-Pa., said after a session with lawmakers. "There was a lot on it."

The major policy legislation Republicans hope to get across the finish line by summer are in addition to traditionally difficult votes to raise the nation's borrowing limit and pass federal spending bills.

The government is operating for the most part off a temporary spending bill that expires in March. Republicans must also pass fiscal year 2018 spending measures in order to provide federal funding beyond the Sept. 30 end of the fiscal year.

"We are being challenged by our leadership to unite on this and being warned there are going to be some tough votes," Collins said. "And the Democrats are not going to help us."

Lawmakers are excited about Trump's appearance Thursday. It will be his first address to the GOP since becoming president.

"He needs to outlay his vision," said Rep. Adam Kinzinger, R-Ill., acknowledging that "there are a lot of different opinions" in the GOP about how to move forward on legislation.

"We are going to have some pretty serious legislation," Kinzinger said. "It's going to be fun, dealing with tax reform, and how to reinvigorate the economy. But it's going to be a lot of work."