WASHINGTON (AP) — The Senate delivered an unexpectedly strong vote Tuesday in favor of taking action later this year to resolve the chronic funding problems that have bedeviled highway and transit programs, a sign that Congress may have reached the limit of its patience with short-term fixes.

The bill, which passed 79 to 18, provides $8.1 billion to keep the federal Highway Trust Fund — the chief source of highway and transit aid to states — solvent through December. That's enough time, supporters said, for Congress to return to work after the November election, when partisan fervor will have cooled, and make the politically difficult decisions on whether to raise federal gas taxes or find some other means to shore up the fund.

The House passed a bill last week that would provide $10.8 billion to keep transportation aid flowing to states through May of next year, with GOP leaders saying more time is needed to deal with the issue. But the Senate rejected that plan in favor of a short-term patch now while setting up a showdown on the matter later this year.

"The Senate has now made a clear and undeniable statement in favor of action on a long-term transportation bill in this Congress," declared Sen. Tom Carper, D-Del., one of three lead sponsors of the bill passed by the Senate. But he also cautioned, "We have a lot of work in front of us to strike the principled compromise that will be needed to pass" a long-term bill.

The trust fund is in its current straits because the federal 18.4-cent-a-gallon gas tax and the 24.4-cent-a-gallon diesel tax— the fund's chief sources of revenue — haven't been increased in more than 20 years, while the cost of maintaining and expanding the nation's aging infrastructure has gone up. The fuel efficiency of cars and trucks is also increasing while people are driving less per capita.

By Friday the trust fund will no longer have enough money to cover promised aid to states, the Transportation Department says, and the government will begin to stretch out payments. States have been warned to expect an average reduction of 28 percent in aid payments.

Without action from Congress, the balance in the fund was expected to drop to zero by late August or early September. Separately, the government's authority to spend money on transportation programs expires Oct. 1. Some states already have cut back on construction projects because of uncertainty over federal funding, and President Barack Obama and state and local officials have complained that the uncertainty over funding is costing jobs.

Before the Senate vote, House Speaker John Boehner, R-Ohio, warned that if the Senate made changes to the House bill, the House would strip out the changes and resend their original bill back to the Senate. Whether or not that happens, lawmakers said a highway funding bill is still expected to clear Congress before the House and Senate adjourn for the summer later this week.

"We won't let the clock run out on transportation funding," said Senate Finance Committee Chairman Ron Wyden, D-Ore.

Three blue-ribbon commissions have called for raising fuel taxes to pay for a mounting backlog of transportation projects, but Congress has avoided doing that in part because it's often unpopular and politically risky. Former Presidents George H.W. Bush and Bill Clinton both ran into political trouble when they signed federal deficit reduction measures that increased gas taxes.

There are other possible ways to pay for highway and transit programs, but so far none that appears to have broad political appeal.