A key minor party is on the verge of directing preferences to the Liberal Party in the WA Senate re-run election, a move that could stop Clive Palmer strengthening his influence in the Upper House.
If confirmed, the Liberal Democrats' decision is expected to help the Liberals secure its third seat.
West Australians are expected to face a record field of candidates on another 1.2m-long ballot paper when they vote on April 5.
Nominations closed yesterday.
The Australian Electoral Commission will reveal the nominees today when it conducts the draw for the ballot order but political strategists expect there to be more than the 62 candidates of September.
Deal-making over preferences is under way but there were rumours last night the Liberal Democrats - which polled 3.43 per cent in September - would favour the Liberals over Mr Palmer's Palmer United Party. The party put PUP ahead of the Liberals in September.
Directing preferences to the Liberals would boost third candidate Linda Reynolds' chances amid the party's fears she could miss out and deprive the Government of a Senate seat where a gaggle of crossbenchers will hold the balance of power.
Liberal Democrats NSW senator-elect David Leyonhjelm said preferencing the Liberals ahead of PUP was being considered.
"If we shore up the Libs and they get three seats, that might cost us in terms of preferences," he said.
"If we went to Palmer before the Libs and we got ahead of Palmer, they might help us get elected. It's a difficult decision for us to make and we haven't made it yet."
When the new Senate sits from July 1, PUP will have two senators plus an alliance with a third, the Motoring Enthusiast Party's Ricky Muir, making the bloc critical to the passage of Bills.
But Mr Leyonhjelm acknowledged his clout on the crossbench would be reduced if PUP got another seat.
He said the Liberal Democrats would "definitely not" give the Liberals their number two preference, saying they would be directed first to other micro parties.
Mr Palmer has written to micro parties promising to stand up for their interests if they gave his party their preferences ahead of the Liberals, Nationals, Labor and Greens.
Labor looks as though it has secured preferences of the minor left-wing Sex Party and Help End Marijuana Prohibition Party ahead of the Greens. In return, Labor will preference them before the Greens.