WASHINGTON (Reuters) - A bipartisan group of U.S. senators unveiled a proposal on Monday to authorize $287 billion in federal government spending over five years to maintain and repair the country’s aging highways, bridges and tunnels, but Congress still faces the tough task of finding a way to pay for it.

The bill, introduced Senator John Barrasso, who chairs the Environment and Public Works Committee, and the top Democrat Senator Tom Carper, along with Republican Shelley Moore Capito and Democrat Ben Cardin is set to be voted on Tuesday at a committee hearing.

It would boost spending by 27 percent over the prior highway bill, but lawmakers must find about $85 billion in additional revenue to pay for those repairs through 2025, officials said. The current spending bill expires in September 2020.

Of the total, $259 billion - or over 90% - would be distributed to states by formula. It would also authorize $6.6 billion for a competitive grant program to address the backlog of bridges in poor condition nationwide among other funding efforts.

In recent years, Congress abandoned the practice of largely requiring road users to pay for repairs. Since 2008, Congress transferred about $141 billion in general revenues to the Highway Trust Fund, according to the Government Accountability Office.

Congress has not boosted the 18.4-cents-per-gallon federal gasoline tax since 1993, which is now worth just 11 cents after adjusting for inflation.

In April, President Donald Trump and Democratic leaders agreed to spend $2 trillion on infrastructure, without hashing out a way to pay for it. Weeks later, Trump abruptly canceled a follow-up meeting after criticizing congressional investigations.

Barrasso spokeswoman Sarah Durdaller said the Wyoming senator would meet with Senate Finance Committee chairman Chuck Grassley, who heads the committee overseeing how to fund the bill, “to discuss how to pay for the legislation responsibly.”

Barrasso “feels that drivers who use the roads should help contribute to maintain them - including drivers of electric vehicles,” she added, noting he has introduced legislation requiring them to pay into the highway trust fund.

The bill would also authorize $1 billion in grants over five years to add new EV charging stations as well as hydrogen fuel cell and natural gas refueling stations.

It would also require the White House Council on Environmental Quality to lead a federal interagency working group “to develop a strategy to transition” government vehicles to electric and other alternative vehicles “to the maximum extent practicable.”