President Trump surprised House and Senate lawmakers in his State of the Union address Tuesday by announcing a proposal to spend $1.5 trillion on the nation’s crumbling infrastructure — a half trillion more than the GOP had anticipated.

“The $1.5 trillion kind of sucked the oxygen out of the room,” Sen. James Lankford, R-Okla., said as he exited the House chamber after Trump’s address.

Republican lawmakers generously praised Trump’s speech, which focused on the nation’s economic recovery, the opioid addiction crisis, immigration reform, and national security, among other topics.

But lawmakers waited eagerly to hear what Trump had to say about an infrastructure bill, which many in the GOP hope will be their main achievement of the second half of the 115th Congress.

Lawmakers did not anticipate the higher price tag.

“Well, we thought it was going to be a trillion,” Sen. Tim Scott, R-S.C., said. “That’s half a trillion higher. There’s that. I’m not sure how we wrap our arms around that shift but in the end we will have a chance to discuss what that means and how we get there.”

The infrastructure bill puts the GOP in a political quandary because of the cost, and raising the price will make it even harder to achieve, lawmakers worried Tuesday.

Republicans have talked of leveraging private money, while Trump, in his speech, said it could be achieved by partnering with state and local governments and, where appropriate, tapping into private sector investment.”

Trump referred to an “infrastructure deficit,” but the GOP is worried about the nation’s deficit, which is growing toward $1 trillion.

Senate GOP leaders seemed miffed at the idea of passing a bill with such a massive price tag and no plan to cover the cost.

“That question is, how are you going to pay for it,” Senate Majority Whip John Cornyn, R-Texas, said when asked about the president’s new infrastructure price tag. “You tell me how we’re going to pay for it and I’ll tell you what we can do.”

Rep. Mark Sanford, R-S.C., said the speech was “a good solid base hit but provided no guidance on how to afford the infrastructure wish list without exploding the deficit.

“That seems to be a mark of the times we live in,” Sanford said.

Even Democrat scoffed at the price tag, despite pitching their own $1 trillion infrastructure plan last year that lacked a way to pay for it.

"Where is that trillion and half coming from?" Senate Minority Whip Dick Durbin, D-Ill., said as he left the House chamber.

Rep. Thomas Massie, R-Ky., a member of the House Transportation and Infrastructure Committee, said the price tag won’t fall entirely on the federal government.

“The president was careful to say it’s going to be a mix of state, local and private money that is going to compose that $1.5 trillion,” Massie said. “I’m looking forward to getting to work on that bill.”

Al Weaver contributed to this report.