Obama is negotiating some kinda deal with all the countries of East Asia EXCEPT China. We think the deal might have some tariff reduction in it. It would be nice to know how much, on what (everything? just left handed smoke shifters? Agricultural goods? who knows?) We hear talk that it will include global warming stuff, pay and benefits to workers, safety standards, all sorts of lefty greeny union stuff. Obama is on TV saying it will be good for us.
Maybe it will, maybe it won't, but since we don't have a clue as to what is in it or might be in it, who knows?
After a lotta wheeling and dealing with the other countries, they might reach a deal. At that point, it's a treaty IF the Senate votes it thru. What the Senate wants to do is amend the deal, changing it unilaterally, and then adopt it. Trouble is, the other counties will back off, because the deal changes will doubtless be bad for them. To prevent Senatorial meddling that breaks the deal, the notion of "fast track authority" was created. Congress passes a special law that forbids amendments and requires a straight up and down vote on the treaty, no funny business. As a rule, without "fast track" a treaty isn't going anywhere.
The US is the biggest market in the world, the biggest economy in the world, and very competitive. Usually trade deals help us by increasing our exports. Other countries do trade deals with us 'cause they want access to the enormous US market. We do trade deals with them 'cause we want to sell our exports there.
On the other hand, Obama is the worst negotiator in the world. Look at how the ayatollahs have jerked him around. He might be able to screw up a trade deal to the point that it looses money for America.