Xenophon undecided on preferences

South Australian Independent Senator Nick Xenophon says the federal government's decision to build the next fleet of submarines in Adelaide isn't enough to convince him to preference the Liberals in the upcoming election.

Senator Xenophon says he's still considering his options, including preferencing either of the major parties or running an open ticket and letting voters decide.

"I'm here to drive a hard bargain for South Australia and I make no apologies for that," he said on Thursday.

"Negotiation 101 means you don't telegraph your punches too early."

Senator Xenophon said it remained to be seen what further commitments might be made by the major parties in the run-up to the election that could tip his hand.

Where the Xenophon team candidates direct their preferences is considered a key to the outcome in a number of seats, especially some held by the coalition in SA.