Robb may have scuttled TPP

Australian Trade Minister Andrew Robb could have inadvertently influenced US senators to deliver another blow to President Barack Obama and the Trans-Pacific Partnership trade deal.

The US Senate is expected to undertake a crucial vote on fast-track authority for the TPP on Tuesday (Wednesday AEST).

Republican senator Jeff Sessions, from Alabama, wrote an open letter on Monday to senators in his party calling on them to vote against the bill and pointed to remarks made by Mr Robb last week in an interview with Australian broadcaster ABC.

Mr Robb said, "We are literally one week of negotiation away from completing this extraordinary deal across 12 countries and 40 per cent of the world's GDP."

The one-week time frame was news to the senator.

"The Australian trade minister has unintentionally debunked the idea that TPP is somehow only in the planning stages," Senator Sessions wrote.

"Some members of congress conditioned their votes on assurances that the (Obama) administration would form the agreement based on the vague, non-binding 'negotiating objectives' in fast-track.

"Those promises are now broken."

The TPP is a Pacific Rim trade deal planned between the US, Australia, New Zealand, Brunei, Canada, Chile, Japan, Malaysia, Mexico, Peru, Singapore and Vietnam.

The nations represent 40 per cent of the world economy.

Mr Obama's hopes of including the US in the TPP hangs in the balance this week with key votes in the Senate.

The president has aligned himself with his usual Republican foes in the US Congress.

Mr Obama, a Democrat, suffered an embarrassing defeat earlier this month when Democrats in the House of Representatives, along with enough Republicans, downed a bill.

The first new hurdle in the Senate will come on Tuesday with a cloture vote on the Trade Promotion Authority bill.

If successful, another vote will be held on Wednesday and if there is enough support, it would be sent to the president for his signature.

The fast-track bill was passed 218-208 on Thursday in the House of Representatives, with support from 28 Democrats.

Democrats are under pressure from unions, the party and Mr Obama's traditional supporters, to reject the bill.

Fast-track will allow Mr Obama expanded powers to negotiate the largely secret TPP with limited oversight from congress.

The TPP, which doesn't include China, has been described as the building block for the world economic order in the 21st century.

It is also a way for the US to keep its global leadership role and help member nations diffuse China's economic dominance in the region.