If there was any doubt that Republicans want to lift the ban on crude oil exports, Rep. Joe Barton (R-Texas) has put it to rest.

Calling the restriction "outdated" in a press release, the conservative congressman from the Dallas suburbs introduced H.R. 5814 this week, which would eliminate the provisions of a 1975 law that has strictly limited the amount of crude that can leave the United States. The move comes ahead of a Thursday hearing on the same topic in the House Energy & Commerce Committee, of which Barton is chairman emeritus.

The bill might strike fear in the hearts of progressives, if only because it signals that Barton is certain to reintroduce it next year, when it will have a much better chance of passing the Republican-controlled Senate.

As long as President Obama remains in power, however, the GOP will need the support of congressional Democrats if they want to override the threat of a veto. And the Democrats should give it to them, but only if they can extract a specific concession: an increase in the federal gas tax.

The end of oil protectionism
To date, the chief progressive argument against allowing U.S. crude exports has been an environmental one, namely that it will encourage more oil production. But on closer examination, this fear doesn't hold as much water as many liberals would like to think.

For one, more oil in the global market will likely drive prices lower. No one is sure at what price point investments in extracting tight oil becomes uneconomical, but the recent crude price drop suggests we may be reaching that level. It is unlikely, then, that lifting the crude ban would lead to the immediate production rush many have predicted.

Furthermore, if the export ban is coupled with a heftier gas tax, over the long term it is likely to constrain runaway emissions growth, as American consumers react to higher prices at the pump and car manufacturers respond with more fuel efficient vehicles.

The right time, the right reasons
One of the government's most pressing needs is to address the gas tax, which when done right allows federal and state governments to combat the detrimental impact of gasoline use by investing in more efficient infrastructure via the Highway Trust Fund.

As it stands, however, the federal gas tax is too meager to do much good. At 18.4 cents per gallon, it only has about 60 percent of the purchasing power it had in 1993, the year it was last raised. At the same time, Americans are driving around 700 million more miles per year than they did two decades ago, making the country's need for increased infrastructure funding even greater.

A litany of commentators has noted that the substantial drop in gasoline prices presents a ripe opportunity to increase the gas tax without placing too much of a financial burden on American consumers. Now that we know for sure Republicans will try to lift the export ban, progressives who have long sought a gas-tax hike should strike a grand bargain with Republican lawmakers who might previously have opposed it.

Key to the plan is the fact that, contrary to popular belief, allowing U.S. companies to ship crude oil overseas would actually lower the price of gas at the pump. According to a recent Brookings report, the decrease would be about 9 cents per gallon.

As a result, the aggregate reduction in prices caused by adding more crude oil to the global market will, all other things being equal, balance out an increase in the gas tax. Americans will pay the same price at the pump, but a greater portion of the money will fund sorely needed infrastructure investment.

Improving the state of the Highway Trust Fund, meanwhile, would address progressives' environmental concerns.

A recent study from the Texas A&M Transportation Institute estimated that road congestion in 2011 produced an additional 56 billion pounds of carbon dioxide in the U.S. Increased infrastructure spending would address this problem not only through new road projects, but also by investing in public transportation via the trust fund's Mass Transit Account.

A golden opportunity
It is a simple fact that our oil use will not change radically in the future. This era of low oil prices could prove to be short-lived, however, which is why the current state of affairs presents a golden opportunity for both parties to make long-desired changes to our energy policy.

Republicans have long complained about what they see as an overly active government role in setting domestic oil prices. Democrats, for their part, would love to see a return to high levels of public-works investment.

A grand bargain would allow both parties to get something they want. In the long run, the whole country will benefit.