Senate Democrats have unveiled a $9 billion plan to prevent states from facing a cutoff of federal highway construction money as early as this summer.

Finance Committee Chairman Ron Wyden, D-Ore., proposed the measure, which would raise taxes on heavy trucks as part of a plan to keep the U.S. highway fund solvent through the end of the year. Trucks over 97,000 pounds would pay $1,100 a year; the current cap is $550 for vehicles over 75,000 pounds.

The measure also tightens reporting requirements for the mortgage interest deduction and toughens the rules for requiring payment of taxes when people under-report income from property sales.

"I hope to see the committee take decisive bipartisan action and send a clear message that stabilizing the Highway Trust Fund is a priority now," Wyden said. "Failure to act now could lead to a transportation shutdown, leaving our roads in disrepair and putting thousands of hardworking Americans out of their jobs."

But Republicans oppose the measure since it relies solely on new revenues to pay for a short-term fix to financing highway projects. Top panel Republican Orrin Hatch of Utah wants a blend of revenues and spending cuts.

"In order to find a real solution to resolve financing for the Highway Trust Fund, the committee must act in a bipartisan manner and forge compromise by including a sizeable amount of reductions in wasteful and low-priority spending," Hatch said.

House GOP leaders have suggested using savings from allowing the Postal Service to end Saturday mail delivery as a way to finance highway projects.

The Finance panel is slated to vote on the measure on Thursday.