President Barack Obama is proposing a $10-a-barrel tax on oil to pay for clean transportation projects, the White House said Thursday.

The tax, which will be part of the budget request Obama unveils next week, would be paid for by oil companies and gradually phased in over five years. It would apply to imported oil, not exported U.S. oil, White House National Economic Council Director Jeff Zients told reporters.

Obama’s proposal lands in the midst of the 2016 election campaigns, and is likely to be harshly criticized by both Republican presidential candidates and lawmakers. In past years, Obama has proposed eliminating subsidies for the oil-and-gas industries. But those efforts have never made it through Congress.

House Majority Whip Steve Scalise of Louisiana said the proposal could be Obama’s worst idea ever.

The tax would add roughly 25 cents to a gallon of gasoline, at current prices.

The White House said Obama’s plan would boost investments in clean transportation by about 50%.

Zients said the administration recognized oil companies would “likely pass on some of these costs” to consumers.

But he added that the U.S.’s “crumbling infrastructure imposes a huge cost on American families,” by reducing competitiveness and by adding time and fuel costs to workers who are stuck in traffic.

Brian Milne, energy editor and product manager at Schneider Electric, said the tax would “definitely” increase gasoline prices.

“Maybe the president thinks because oil and gasoline prices are low, he can slip the tax through that will eventually be passed on to consumers without many realizing that they’re paying the government more to fuel their vehicles and warm their houses,” Milne said in an email. “However, I don’t think it will have enough support to move through Congress.”