Obama says Pacific trade deal can be struck 'this year'

US President Barack Obama on Wednesday expressed optimism that a vast Pacific trade deal can be reached before the end of the year, despite disputes over rules for key sectors.

Discussing a 12-country pact that brings together large and growing economies as diverse as the United States, Japan and Vietnam, Obama told business leaders, "I have confidence we can get it done and I believe we can get it done this year."

"Trade ministers should be meeting again sometime in the next several weeks, they have the opportunity to close the deal," Obama said.

"Most chapters have been completed at this point," he said, adding that the deal would "make sure that we have a level-playing field for businesses and American workers in the fastest-growing region of the world."

Already eight years in the making, the Trans-Pacific Partnership (TPP) would be a huge bloc encompassing 40 percent of global trade and part of Obama's much-vaunted "pivot" towards Asia in the face of an increasingly assertive China, which is not included.

The failure by trade ministers to wrap up the accord in August in Hawaii was a blow to Obama -- who faces opposition to the deal from fellow Democrats -- as it could see the TPP become campaign fodder ahead of November 2016 elections.

With Congress requiring 90 days to review any accord, a vote is now unlikely before 2016 even if a deal can be reached.

That raises the risks for Democrats already struggling to explain their vote in favor of negotiations to donors and constituents.

Efforts to move to a final round of ministerial talks have also been complicated by elections in Canada on October 19 and a change of prime minister in Australia.

Australia's new leader Malcolm Turnbull faces a stiff task to revive an economy at risk of suffering its first recession in 25 years.

He has already been portrayed by the opposition as an out-of-touch millionaire and will be under pressure to push a hard line ahead of elections expected next year.

In Canada, Prime Minister Stephen Harper faces a tough three-way reelection fight, and may also be forced to take a tougher stance on opening up Canada's dairy market to more competition.

None of Canada's three major parties publicly oppose the deal and US officials insist there is no reason why developments there or in Australia should scupper talks.

Nonetheless, negotiators may seek to play it safe and conclude an agreement before the October vote in Canada.

Informal talks are already under way to find a breakthrough on outstanding issues including rules for the auto trade and protection for drug-makers and dairy farmers.