In 2015, current Democratic presidential candidate Beto ORourke twice bucked his own party to vote with Republicans to end the 40-year restriction on selling U.S. oil overseas.

In October that year, ORourke voted on a bill to outright lift the ban. But the legislation stalled in the Senate. In December, he voted to approve an amendment to a budget bill that ultimately passed in the Senate.

The export proposal, which the League of Conservation Voters called anti-environment , helped flood global markets with U.S. oil just as fossil fuel emissions rapidly warmed the planet and threatened catastrophe within a generation. Its also a mark against ORourke, whose record on climate change is facing new scrutiny as his presidential campaign heats up.

At the time, ORourke called the export ban outdated policy and said lifting it means that America can compete with other oil-producing nations and make allies less dependent on energy from other volatile areas in the world.

Now, as the United States is poised to surpass Saudi Arabia as the worlds No. 1 oil and gas exporter, his campaign has echoed that defense.