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

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 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," Clinton, the Democratic presidential front-runner, said Monday in Concord, New Hampshire.