A considerable sum probably get their supply chain from overseas, where reduced tariffs and so on would help them. That's the point behind free trade and deals like NAFTA and so on.
The supply chains we see for materials and goods are global meaning structured free trade deals are actually a key component of our growth.
Most modern trade deals are not about tariffs, and are mostly about foreign investment and dispute resolution. The US already has generally low tariffs, and the majority of businesses, large or small, do not source from TPP countries in material amounts, and if they do, the portion of their costs they are most concerned about is freight, not tariffs. The only companies that regularly deal with tariffs are those with manufacturing plants overseas and import/distribution firms. Even then, we are only talking about the lowest value products being produced in these countries, like coffee, rubber, and textiles.
High-value proprietary imports like tools, machine parts, and chemicals are usually sourced from Japan, Germany, or other European countries. (I do realize that Japan is in the TPP, but nobody is pretending that TPP is about US/Japan trade) Most businesses are not really affected by TPP either way, and the ones who are strongly in favor of it are multinationals who want the investment opportunities, dispute resolution mechanisms, mutual standards, and perhaps lower input costs.
