One of the most basic facts about the Trans-Pacific Partnership is also the most important: It's huge.

The trade deal got over a big hurdle Friday when the Senate voted in favor of giving the Obama administration "fast-track" authority to negotiate the deal with Canada and 10 Asian nations.

That leaves the U.S. House, and it's unclear it has the votes yet. If it passes, though, TPP, which has angered many in the president's party, would be by far the largest free trade agreement the U.S. has in effect.

The 12 nations involved in TPP make up about 36 percent of global gross domestic product, or GDP, according to data from the International Monetary Fund. That sets the TPP well apart from the 14 free trade agreements the U.S. currently has in effect with 20 countries (to be fair, the U.S. accounts for nearly 23 percent of global GDP by itself).

Not only that, but these nations together account for about one-third of global trade, according to the Brookings Institution.

So the TPP stands apart from other trade agreements in its size. But that's only one dimension of its impact. Another way the TPP is gargantuan is tougher to quantify in a bar graph: its scope. It not only covers basic trade issues like tariffs, but also a variety of other areas like labor and environmental and intellectual property.

The size and scope of TPP matter because they are at the center of the debate. The Obama administration sees the deal's broad reach as positive — the agreement, the administration says, will open up the U.S. to all kinds of new markets and business.

Agribusiness companies, for example, are excited about having new avenues for their products. The labor and environmental provisions, the administration also argues, will force other nations to up their game on those issues, "leveling the playing field."

Not only that, but the TPP's size is all the more important for the one economic superpower that isn't included in it: China. One of the administration's top arguments for the deal is that in negotiating TPP, it "writes the rules" for trade with a large swath of eastern Asian countries before China can with its own trade agreements.

But opponents, like Sen. Elizabeth Warren, D-Mass., worry about the sweep of the deal. Leaked chapters have intellectual property advocates, like the Electronic Frontier Foundation, worried it goes too far in areas like extending copyright laws and fair use rules. Doctors Without Borders has also argued the deal could make for more expensive generic drugs, restricting access to medicine for some consumers.

However, some wish the pact went further — environmental groups like the Sierra Club, for example, believe the provisions won't do enough to address overfishing.

But then, no one outside members of Congress, negotiators and a small group of cleared individuals has access to the pact, so it's hard to know exactly how far it will (or won't) go. And that is perhaps the source of the most tension in the TPP debate: that such a big deal is being negotiated behind closed doors.

If Congress grants the administration fast-track (also known as Trade Promotion Authority), it will mean two to four months for public comment before Congress gives the deal an up-or-down vote, with no amendments or debate.

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