US President Barack Obama, with House Democratic leader Nancy Pelosi, walks from a meeting room after making a last-ditch appeal to House Democrats to support a package of trade bills vital to Trans-Pacific Partnership.

US President Barack Obama has been cleared to "fast-track" talks on the Trans-Pacific Partnership - but the lawchange is stuck as lawmakers haggle over a bill providing worker aid.

In a dramatic vote, Obama's own Democrats, as well as Republicans, failed to produce enough support to approve a bill that would have given aid to workers who lose their jobs as a result of US trade deals with other countries.

The measure was soundly rejected in a 302-126 vote.

That was quickly followed by the House's narrow approval of a separate measure to give Obama "fast-track" authority to negotiate the Trans-Pacific Partnership trade deal.

But the legislation is stuck in the House because of the defeat Obama and House Speaker John Boehner suffered on the first vote.

A House Republican aide told reporters that Republican leaders hope to try again on Tuesday (Wednesday, NZT) to pass the worker aid portion of the bill, allowing the measure to be signed into law by Obama, but its chances were unclear.

Trading partners such as Japan have urged the US Congress to act in order to help wrap up a Pacific Rim trade deal covering 40 per cent of the world's economy.

Obama had lobbied hard to win over sceptical Democrats and forged an unusual alliance with the Republicans who control Congress, and made a last-ditch personal appeal to congressional Democrats to back his trade agenda on Friday (Saturday NZT).

Hours before divided lawmakers were due to vote on legislation central to his hallmark Pacific Rim trade deal, Obama arrived at Capitol Hill with Labour Secretary Thomas Perez for the culmination of an intense effort to build support among Democrats over the last 24 hours.

But shortly before the doomed vote, some of Obama's fellow Democrats signalled that the president's efforts at persuasion had failed.

Democratic Representative Danny Davis, who represents Obama's hometown of Chicago, said on the House floor: "I don't want a fast track. Matter of fact, the jobs and economic development have left the communities I represent fast enough."

Republican support was always weak for the worker aid part of the "fast-track" trade legislation and Democrats' support eroded this week following an intensive lobbying campaign by US organised labour leaders.

The AFL-CIO, the country's largest labour organisation, argued that funding for the worker aid programme would be insufficient.

But it also rallied support for its cause by arguing that a vote against worker aid would be the perfect tactic for stopping fast track dead in its tracks.

Fast-track authority would let lawmakers set negotiating objectives for trade deals, but restrict them to only a yes-or-no vote on the finished agreement.

Many Democrats have worried that giving Obama fast-track authority to finish the 12-nation Trans-Pacific Partnership (TPP) trade deal would result in job losses in their home districts just as the United States was making economic gains that have led to a brightening jobs picture nationally.

Boehner, the top Republican, in consultation with House Democratic leader Nancy Pelosi, is expected to weigh next steps.

For example, they could try to make some changes to the worker training programme or schedule more one-on-one meetings with lawmakers to allay their concerns.

The Senate, in a strong bipartisan vote, has already approved the package of trade measures, which includes a customs enforcement bill.

House Republicans have loaded that bill down with controversial language designed to tie Obama's hands on immigration and climate change initiatives, further complicating the entire trade fight.

Senate Democrats are expected to stand in the way of those measures.