A man prepares to fill a vehicle with fuel at a Pilot Travel Center gas station in Cornersville, Tenn. (Luke Sharrett/Bloomberg)

President Trump privately suggested massively increasing the gas tax to help fund a national infrastructure overhaul, but Republican leaders in Congress moved quickly to shut down the idea.

During a White House meeting with House Transportation Committee Chairman Bill Shuster (R-Pa.) several weeks ago, Trump mused about a gas tax increase to 50 cents per gallon, almost triple the current level, according to a person briefed on the exchange who requested anonymity to discuss White House deliberations.

The White House declined to comment on the exchange, and Shuster declined to discuss the conversations with the White House, calling them “completely private.”

Trump, Cabinet members and GOP leaders also discussed the gas tax increase during joint meetings this weekend in Camp David. Sen. John Cornyn (R-Tex.), who attended the meetings, would not reveal who raised the subject of raising the gas tax, but he said there was no ambiguity about how Congress planned to proceed.

“I’m sure it came up in some context because that’s what a lot of people have proposed at different times,” Cornyn said. “But I have complete confidence that we will not be raising the gas tax.”

The discussions underscore the difficulty Trump faces as he seeks to finance his 2016 campaign promise of a $1 trillion national infrastructure upgrade. Trump has said the infrastructure spending is central to his economic agenda, and he believes the investments could create millions of new jobs across the country.

The White House is expected to release an infrastructure plan as soon as this month, but that plan is not expected to dictate how the projects would be paid for, in part to avoid controversy and preserve flexibility.

Though a potential source of significant revenue, increasing the federal gas tax has remained politically tenuous, as critics say it disproportionately harms poor Americans because they are less able to absorb such changes in fuel costs. Many Republicans have consistently opposed past proposals for increases, though some have said they are open to such a move.

The current federal fuel tax is 18.4 cents per gallon for gasoline and 24.4 cents per gallon for diesel fuel. The gas tax was last raised in 1993, and it is not indexed to inflation. The tax mostly finances the Highway Trust Fund, with a very small portion going to the Leaking Underground Storage Tank Trust Fund.

Because the federal government has not raised the gas tax in 24 years, a number of states have raised their own gasoline taxes to fund state projects.

White House officials said they still have not made a final determination as to whether they will pursue an increase in the gas tax, even though GOP leaders have made clear an increase will not have enough Republican support to become law.

A White House spokeswoman said the concept “hasn’t been taken off the table, as most previous administrations have done.”

“The goal is to move away from Washington dictating to states what they need to do, so I wouldn’t expect what the administration rolls out to be that explicit in regard to gas tax, tolling” or other ideas, the spokeswoman said.

Trump had made similar gas tax comments to Bloomberg during an April interview, saying an increase was “something that I would certainly consider . . . if we earmarked money toward the highways.”

Several Republicans had echoed Trump’s openness to boost the gas tax, saying it was one way to raise money for infrastructure projects. “I’m still open to it,” said Sen. Mike Rounds (R-S.D.)  Tuesday after meeting with White House officials about infrastructure plans for this year.

And Shuster said he could not guarantee the gas tax would not be increased.

“What I’ve said for the past couple of years is everything should be on the table,” he said when asked if the proposal was still under consideration. “Guaranteeing anything in Washington is folly. We can’t guarantee anything.”

A number of Democrats, meanwhile, have clamored for a gas tax increase, saying it is needed to fund improvements to the nation’s infrastructure. Rep. Peter A. DeFazio (D-Ore.) proposed essentially raising the gas tax 1 cent per year in a way that he said would raise $500 billion over 30 years to pay for infrastructure projects.

White House aides have said the president’s broader infrastructure plan would be designed with $200 billion in federal funding and rely on states, localities, or private investors to cover the remaining $800 billion, but Trump has waffled on this, saying he doesn’t believe partnerships between the federal government and private investors would work.

President Barack Obama did not propose increasing the gas tax, but he did propose a $10-a-barrel tax on crude oil that could have effectively raised the gas tax because companies would pass those costs on to consumers. The Obama administration projected that would raise $65 billion a year when fully phased in.

Reporter Steven Mufson contributed to this report.