President Trump said he could support a 25 cent increase in the federal gas tax during a Wednesday meeting with lawmakers.

Sen. Tom Carper, D-Del., who participated in the meeting, told the Washington Examiner that Trump “offered his support” for raising the gas tax.

“To my surprise, President Trump, today in our meeting, offered his support for raising the gas and diesel tax by 25 cents a gallon and dedicating that money to improve our roads, highways, and bridges,” said Carper, the top Democrat on the Senate Environment and Public Works Committee. “While there are a number of issues on which President Trump and I disagree, today we agreed that things worth having are worth paying for, and the president even offered to help provide the leadership necessary so that we could do something that has proven difficult in the past.”

The tax, which has not been increased in 25 years, is currently 18.4 cents for gasoline and 24.4 cents for diesel.

The White House is refusing to confirm whether Trump supports raising the tax. A spokeswoman reaffirmed the administration’s position that “everything is on the table” when it comes to paying for Trump's infrastructure plan, and said those details would be left to Congress.

Some Republicans have said they would support an increase.

The U.S. Chamber of Commerce recently called for the Trump administration and Congress to raise the gas tax by 25 cents per gallon to help pay for an infrastructure package, projecting it would generate more than $375 billion over a decade.

The Republican chairman of the House Transportation and Infrastructure Committee, Rep. Bill Shuster of Pennsylvania, prodded colleagues at the recent GOP retreat to consider setting aside years of opposition and raise the tax.

Opponents argue the gas tax is regressive, since it is a fixed fee imposed on everybody who pays it, no matter their income. As a result, poorer people pay a larger percentage of their money on the tax.

Sen. John Barrasso, R-Wyo., the chairman of the Environment and Public Works Committee, told the Washington Examiner he will resist an increase of the gas tax.

“Today was the first of many conversations about the president’s infrastructure plan and how to fund it,” Barrasso said Wednesday after he participated in the White House meeting with Trump. “Speaking for myself, I oppose raising the federal gas tax. The gas tax isn’t a pure user-fee. Not everyone who uses the roads today pays the tax and not all of the money collected goes towards fixing America’s aging roads and bridges. Ultimately, the final decision will be made by Congress as a whole.”

Trump released his long-awaited infrastructure plan this week that proposes providing $200 billion in federal money to spur at least $1.3 trillion in spending from state and local governments and private industry.

But the Trump administration has provided little insight into how it would pay for the plan.

The federal government does not have a long-term funding source for transportation and has been reluctant to increase user fees such as the gas tax.

The combination of a gas tax that hasn't changed in 25 years and the greater fuel efficiency of cars has led to chronic shortfalls of more than $70 billion since 2008 in funding for the Highway Trust Fund, the main vehicle to spread money to states to help pay for transportation projects.