The Turnbull government is facing a war with the majority of the Senate crossbench after it unveiled its plans for voting reforms that could wipe out the minor parties and independents by making it much more difficult to engineer preferences deals and game the system to get elected.

The "optional preferential" voting reforms could pave the way for a double dissolution election in July that would radically reshape the Senate, and come after a deal was negotiated with the Greens and independent Nick Xenophon over the reforms.

Prime Minister Malcolm Turnbull said the changes would ensure that Australian voters would determine where their Senate votes go, rather than having those preferences allocated by complicated back room deals.