The fate of the Keystone XL pipeline has dominated politics for the first few weeks of 2015, and it will continue to do so after the Senate follows the House's lead in passing legislation that fast-tracks its construction. The oil industry continues to campaign for the pipeline, but thanks to plummeting gas prices and a glut of oil production, a new issue is emerging as its top priority for 2015: scrapping a 40-year-old ban on crude oil exports. 

“Perhaps no issue better captures the potential and ongoing tension between America’s 20th-century energy reality—a reality of scarcity and dependence—versus our 21st-century reality — one of abundance and energy leadership,” American Petroleum Institute President Jack Gerard said last week.

The policy has been in effect since the 1970s, following a spike in oil prices during the Arab oil embargo. The first cracks in the ban appeared last year, when the Obama administration allowed lightly processed crude oil to be exported. This has emboldened GOP calls for a full repeal. On Monday, according to Politico, Senator Ted Cruz announced his plans to offer an amendment to the Keystone XL bill that would end the ban. The initiative has some powerful allies, including Senate Energy and Natural Resources Committee Chairwoman Lisa Murkowski, who has steered efforts to introduce a lift-the-ban bill in Congress. Recently, the industry stepped up its political push when 16 oil companies formed a first-ever lobbying group, Producers for American Crude Oil Exports, focused solely on that outcome. 

This isn’t as clear cut a partisan issue as Keystone. It unites environmental Democrats with refinery companies, which have seen profits surge as a result of rising domestic oil production. Even some Republican politicians are wary of lifting it, because the majority of voters prefer keeping it in place. According to a poll conducted by the liberal Center for American Progress, more than two-thirds of both parties would rather see the U.S. prioritize expanding refinery capacity over changing policy on crude oil exports. It would be disastrous politically if the repeal were followed by a gas-price spike.

Both sides seem to agree on one thing: Lifting the ban would increase domestic oil production. But it's not clear what that would do to gas prices.

Oil companies say it will lower prices, and point to studies (many backed by the industry) supporting this. “Allowing producers to sell crude oil on the global market is a win-win for the U.S. economy and for consumers, who will benefit from job creation, lower gasoline prices and other economic benefits,” a Marathon Oil spokesperson said by email. 

Critics say U.S. domestic production is far too small a percentage of total global oil supply to have an impact on prices. The Energy Information Administration hasn’t taken a side, but reported in October, "The effect that a relaxation of current limitations on U.S. crude oil exports would have on U.S. gasoline prices would likely depend on its effect on international crude oil prices, such as Brent, rather than its effect on domestic crude prices." The Congressional Budget Office, meanwhile, found that a repeal “would probably lower world prices of oil and of liquid fuels produced from oil, but only slightly, and changes that left some export prohibitions in place would lower world prices even less."

The impact on the climate is a bit clearer. Rising production could pose a problem for the U.S.’s goal of reducing carbon emissions by up to 28 percent by 2025. A recent University College London study published in Nature argued that 10 percent of oil and gas reserves in the U.S. will need to stay in the ground in order to avoid more than 2 degrees Celsius of warming