Today, the House will either advance—or imperil—President Obama’s trade agenda when it votes on legislation to give him more power to ink deals with other nations.

For Obama to win the power he craves, he will have to lean heavily on Republicans—and hope just enough Democrats side with him—showcasing the odd alliances that have defined the trade battle.

The debate is about what’s known as trade promotion authority. Fast-track trade authority, as it’s better known, would leave Congress with the power to vote up or down on trade deals but with no ability to amend such deals.

Obama says he needs such power to assure the 12 countries involved in the Trans-Pacific Partnership—which would link 40 percent of the world’s economy—that Congress won’t unravel it.

The Senate already barely passed legislation giving Obama trade promotion authority.

In a sign of how tight the vote will be in the House, the chamber narrowly passed a procedural rule Thursday that allowed the trade vote to occur today.

The rule passed 217-212, with 34 Republicans voting against it and eight Democrats backing it. Democrats rarely vote with Republicans on such procedural motions; without the eight Democrats, the measure would have failed.

>>> See How Your Representative Voted on the Rule

The tight vote foreshadows the challenge today, when the House will vote on trade promotion authority and a separate bill offering money and training to workers displaced by trade.

Some conservatives are urging the House to oppose the bills.

“Free trade is good for all Americans, but this fast-track authority has gotten bogged down in the politics of corporate welfare, protectionism and labor union handouts,” said Dan Holler, a spokesman for Heritage Action, the sister organization of The Heritage Foundation.

But others believe trade promotion authority will help the United States set a free-market agenda around the world—no matter who’s leading the negotiations.

“In order to understand it, you need to eliminate the personalities and take the name Obama out of it,” said Rep. Mike Kelly, R-Pa., in an interview with The Daily Signal. “I am voting for it because I think it’s the smartest thing. I don’t call it fast track. I call it safe track because we have the oversight—we being Congress. We’ll make sure we protect American jobs, and, by the same token, protect the world.”

Learn more about the fight over Obama’s trade agenda in the video above.