WASHINGTON (AFP) - Senate Majority Leader Harry Reid announced his opposition to trade promotion legislation, tossing a wrench into White House efforts to build congressional support for massive free-trade deals with Asia and Europe.
"I'm against 'fast track,'" Mr Reid bluntly told reporters on Wednesday, a day after President Barack Obama called on Congress to pass such a tool to help open new markets for American products.
Asked if he will prevent such trade promotion authority legislation from going to the floor for a vote, Mr Reid said "we'll see," adding, "I think everyone would be well advised just to not push this right now."
TPA would allow Congress to pass or reject the deals on simple up or down votes, barring lawmakers from changing results of the delicate, years-long negotiations between Washington and other nations.
Obama seeks to forge stronger trade ties with Pacific Rim nations as part of Washington's pivot to Asia.
His administration has placed a high priority on the 12-nation Trans-Pacific Partnership (TPP) at a time of rising China clout.
And a free-trade deal with Europe would be the world's biggest.
The EU estimates it would bring annual benefits of 119 billion euros (S$207 billion) for the bloc's 28 member states, and only slightly less for the United States.
Many labour groups opposed such deals because they would increase competition and potentially lower labour standards.
Consumer and environmental organisations - also usually reliably in Obama's camp - not to mention liberal Democrats in Congress, are deeply skeptical of ramming through such massive deals without elected officials having a chance to weigh in.
"I think there's a great deal of public concern coming from the fact that there's so much secrecy of the content, of the draft that nobody's seen," liberal Senate Democrat Jeff Merkley said of the TPP.
"There needs to be a full public vetting of the content."
Last week, 151 of the House's 200 Democrats wrote the president expressing their opposition to fast-track. Hundreds of outside groups did the same.
Business groups like the US Chamber of Commerce have lobbied hard for the deals. And several Republicans, thrust into a rare alliance with a Democratic president, expressed concern that Mr Reid effectively put both trade deals on ice.
Mr Reid's opposition marks "a significant threat" to the Asian and European trade pacts, Senator Marco Rubio told AFP.
Mr John Cornyn, the Senate's number two Republican, agreed.
"I think Harry and the president need to have a conversation and figure out what they're going to do," he said.
Mr Reid earned the wrath of Tony Fratto, an international trade adviser in the George W. Bush White House, who said the Senate leader stood opposed to policies by Republican and Democratic presidents alike who have championed trade expansion.
"Reid pulled the rug out from maybe the only bipartisan economic policy left in Washington, and kicked the president in the shins for good measure," said Mr Fratto, now a managing partner at Hamilton Place Strategies.
Mr Obama was able to get free trade deals with Colombia, South Korea and Panama passed by Congress in 2011 under fast-track authority approved during Mr Bush's presidency, but that permit has since expired.