Nationals demand TPP sweeteners

A controversial 12-country Pacific trade pact could become a reality by week's end, so long as some give and take can be reached on sugar.

Trade Minister Andrew Robb is in Hawaii for what's hoped to be the final round of Trans-Pacific Partnership negotiations.

Sugar is proving a sticking point at the bargaining table.

Mr Robb insists he won't sign a deal that doesn't offer some sweeteners to sugar farmers.

But half a dozen federal National MPs have vowed to cross the floor when the agreement comes before parliament if only a token result is achieved.

The US allows sugar imports on a quota system, with Australian cane farmers now allowed to send about 100,000 tonnes there each year.

The farmers would like to boost this to more than 500,000 tonnes but the Americans are holding out.

Queensland senator Matt Canavan maintains Australia needs to play hard ball.

"It's important that we send a very loud and clear message to our negotiators and the rest of the world that this is a showstopper for us," he told AAP.