WASHINGTON (AP) — Despite formidable opposition across the political spectrum, President Barack Obama is using his final months in office to fight for congressional approval of a 12-nation free trade pact called the Trans-Pacific Partnership. Back home, presidential candidates Hillary Clinton and Donald Trump bash it and public opinion polls indicate voters are closely divided on the agreement's merits. Last year, the House barely passed legislation establishing a streamlined process for approving TPP, called "fast-track," but the details of the actual agreement were not made public until November. [...] about a dozen Republicans who voted for the fast-track process have switched and said they oppose the deal, seemingly eliminating a narrow cushion of support. [...] he says it's good for the economy because it eliminates thousands of tariffs that will lower the price for American-made goods and services. [...] it's good for U.S.