WASHINGTON - Mrs Hillary Clinton has complicated President Barack Obama's quest for fast-track authority on his Pacific trade pact by throwing her support behind fellow Democrats who revolted against the measure last week, while the US Congress further delayed action on related legislation.

Mrs Clinton's criticism on the presidential campaign trail further dimmed hopes of reviving the White House's drive for the Trans-Pacific Partnership (TPP) in Congress, a key piece of legislation in Mr Obama's second term.

"I believe that one of the ways the President could get fast-track authority is to deal with the legitimate concerns of those Democrats who are potential 'yes' voters to see what's in the negotiation or even what's in the existing framework agreement that is being drafted, could be modified or changed," Mrs Clinton, who is seeking her party's nomination for the presidency, said on Monday.

Republicans, who control Congress and want more time to rescue Mr Obama's trade agenda, moved to postpone a House vote expected yesterday, setting a July 30 deadline for future action.

"We remain committed to getting (fast-track) done, and this will give the President more time to communicate the consequences of not moving forward with his party," said a Republican party spokesman.

Mr Obama's own Democrats last Friday derailed his push for authority to speed trade deals through Congress with a yes-or-no vote, casting doubt on the trade pact central to the administration's pivot to Asia.

Mr Edward Alden, a trade policy expert with the Council on Foreign Relations, said any late tweaking of the deal to appease Democrats could cost the trade pact broad support elsewhere. "In doing what secretary Clinton is recommending, the administration could well lose the support it has on the Republican side," he said.

Mr Obama would need to persuade almost 100 fellow Democrats to support the landmark trade Bill.

Since her campaign entered a more expansive phase last Saturday, Mrs Clinton has made it clearer that she is actively courting the left wing of the Democratic Party, which fears the trade deal would hurt American workers.

"The President continues to be confident we will navigate this particular procedural snafu and move this across the finish line," White House spokesman Josh Earnes said.

REUTERS, BLOOMBERG