The tariff-slashing Trans-Pacific Partnership (TPP) has turned into a hot-button topic in the run-up to the Nov. 8 U.S. election, threatening to dampen support from lawmakers needed to pass a deal critics condemn as a job-killer.

U.S. Trade Representative Michael Froman said he was still optimistic Congress would pass the 12-member TPP, in part because China has been moving ahead with a trade deal of its own, the Regional Comprehensive Economic Partnership (RCEP), that would boost its exports and let it set labor and environmental standards in the fast-growing Asia Pacific region.

"We're one vote away from either cementing our leadership in this region and in the global trading system or ceding it to China," Froman told reporters in Lima after attending the inauguration of Peruvian President Pedro Pablo Kuczynski.