(Rogelio V. Solis/AP)

GASOLINE PRICES are down across the country, and they might stay relatively low for a while, which means that Americans will feel less constrained about using the nation’s roads. But the way Congress approaches building and maintaining those roads remains one of Washington’s great examples of congressional dysfunction, an inadvertent policy of near-delinquent federal behavior that regularly jolts transportation officials and construction companies across the country into unneeded anxiety. Even in this age of partisanship, prominent members of both parties agree that they should be able to work out a better system. It’s about time that happened.

For years, Congress has faced funding shortfall after funding shortfall in the federal transportation budget, creating the sort of uncertainty that discourages long-term plans. Each time, instead of fixing the problem, lawmakers have pushed it off with temporary, patched-together budget gimmicks. The most recent patch will run out next spring. But Congress can’t just sit back and watch the clock tick away. Unsurprisingly, that strategy has yielded only more last-minute gimmicks. Once and for all, lawmakers should fix the underlying problem and put the nation’s Highway Trust Fund on sure footing.

House Speaker John A. Boehner (R-Ohio) said this week that transportation funding is one of a couple of issues on which Republicans and President Obama can deal. In the Senate, a bipartisan group including Barbara Boxer (D-Calif.), Thomas R. Carper (D-Del.) and Bob Corker (R-Tenn.) continues to push a serious reform proposal, hoping that lawmakers will get to it as early as Congress’s lame-duck session several weeks from now.

The plan is a good one. The underlying problem is that gas tax revenue, the foundation of the federal Highway Trust Fund, is no longer sufficient to finance the nation’s roads and rails. That’s in part because Congress hasn’t raised the tax since 1993. The Senate bill would do so in two steps, then index the tax to inflation, a long-term plan lawmakers should have adopted years ago.

Of course, the dynamics in Congress aren’t quite as simple as this obvious, off-the-shelf policy solution. Many lawmakers may still shy away as they have before, betting that taxing gasoline is bad politics, no matter how much — or how little — people are paying at the pump. Many Republicans also want to wait for a while before taking on the problem, pushing the debate deep into next year. That may be because they want time to enact a corporate tax reform that would generate a one-time windfall for the government, then use that to shore up the Highway Trust Fund for a few more years. Rep. Paul Ryan (R-Wis.) lauded that idea on Fox Business Network this week. Mr. Obama endorsed it this year.

That strategy would be better than some of the gimmicks Congress has used, mostly because it would last for a while and allow for longer-term infrastructure planning. But it would still be a one-time patch. Instead of waiting longer to pass unimpressive reform, Congress should make the rational policy change — fixing the gas tax — as soon as it gets back from the campaign trail.