The Turnbull government would seize a rare, absolute majority in the Senate if it finalises a deal on voting reform and calls a double-dissolution election, according to two experts on the preference system.

The Greens - who are negotiating with the Coalition to end "preference harvesting" among minor parties - would likely lose two of its current 10 senators if it agrees to support reforms and both houses of Parliament are dissolved.

A review of voting data by Graham Askey and Peter Breen, veteran players in minor party preference negotiations, forecasts the Coalition would win 40 Senate seats - a gain of seven - while Labor would remain anchored at 25 under the proposed changes being sought by the government.

Nick Xenophon, who is pushing to abolish the group voting ticket - the mechanism that allows minor parties to transform a tiny primary vote into seats in the Senate through preference deals - would be the biggest winner, with two new senators joining him in Parliament, according to their projections.