What is “The Trans-Pacific Partnership”and why is it political ??

Legally what it is by definition.

The Trans-Pacific Partnership (TPP) or Trans Pacific Partnership Agreement (TPPA) is a trade agreement among twelve Pacific Rim countries. The finalized proposal was signed on 4 February 2016 in Auckland, New Zealand, concluding seven years of negotiations. It is currently awaiting ratification to enter into force. The 30 chapters of the agreement aim to "promote economic growth; support the creation and retention of jobs; enhance innovation, productivity and competitiveness; raise living standards; reduce poverty in the signatories' countries; and promote transparency, good governance, and enhanced labor and environmental protections."[5] The TPP contains measures to lower trade barriers, such as tariffs, and establish an investor-state dispute settlement mechanism.

The politics is far more confusing.

When you go to Walmart ( and you KNOW you do ) chances are the item,even food,comes from  a country with a pacific ocean border.We live in a global economy and WE have demanded more affordable products so if its made somewhere else,it matters not as long as it cheaper and similar quality.
Now as workers who have a standard of living much higher than the countries that we now buy these products from,we face a conundrum.We have created a demand that american business will fill,Its what yankee traders have always done through out history. There are unintended consequences however.We had factories that made these products and demands are now higher as we buy more,thus,business expands BUT demands from its stock holders to keep the bottom line are strong.Business always looks at its work force as a asset like any plant equipment and will trim that asset and substitute it will a foreign asset to maintain that bottom line.
Not to get into the whole labor/management thing,thats why plants go overseas,nothing more.Its just business nothing personnel.Simple enough,BUT thru time foreign workers see what they make and can’t afford and as in Chinas case,that government allowed a limited form of capitalism to allow its workers to buy what they made.A middle class,what a novel idea!!!

So if you follow that,China now must now complete with OTHER countries who are less labor intense than they are becoming.Mao would be turning in his grave to see how much its shifting in our direction although its still a theocracy.More counties are becoming producers and have not yet felt the demands of a growing work force into a middle class as China,Korea and Japan have felt.Vietnam oddly enough may be next.

Now with this come global terrorism.Asia is awash with Islam and the clash of western values by this new global economy is largely to blame for the internal clash within it.While this is NOT about that it is a unavailable byproduct.Within Islam a womans body must be hidden and western industry sexualizes it by nature even on TV and print,so its very complicated.Just think”Honor Killings”.
However the genie has been released and Islam struggles to live with it.

So when we say NO TPP what are we saying? When you buy a Trump tie what are you buying?
By nature its a conflicting issue.However as drug criminals around the world have said,cut the demand and they are out of business.If you want a cheaper car and better iPhone and computers and affordable fresh food,what are you to do?? To simply say bring plants and produce here IGNORES our own consumer greed that sent them overseas to begin with.The TRUTH hurts.Now we are losing jobs faster than anyone ever foresaw,that is true as well.However consumer wise we still have enough people at work with enough income to drive this global economy BUT it is shrinking and as China’s middle glass grows we lose less control,Complecated??You bet you,opps gambling term,by the way Macau China is the NEW Las Vegas and Singapore is the new New York.

What to do?? First cut through blind rhetoric and truly understand the issue.The old jobs are NEVER coming back.We have to educate our kids to develop new technologies,thats always what we really did.Industries have to realize if they continue to leave the US in shortsighted efforts to shield products and profits they risk a long term danger of nationalization or worse in a developing hostile world of angry and populous nations whose leaders must control their populations by any means available.All while WE want more STUFF.
See the problems??