B.C.'s premier and the leader of the Green Party hope to spur more participation in the province's proportional representation referendum by appealing directly to voters.

John Horgan and Andrew Weaver headlined an event on Sunday dubbed as a proportional representation day of action in Vancouver.

The two leaders spoke to volunteers about the importance of participating in the referendum before hitting the streets and knocking on doors to canvass residents about sending in their ballots.

The push comes as Elections BC says it has received less than 20 per cent of ballots, which need to be mailed by Nov. 30.

Voters are being asked whether they want to maintain the existing first-past-the-post system for provincial elections or switch to one of three different types of proportional representation.

The Vote No campaign has raised concerns about the referendum, saying an extension is needed because of the potential for low voter turnout and mail delivery disruption from the Canada Post strike.

Have you received your electoral reform voting package? If not, you have until Nov. 23 to request one from Elections B.C. (Elections BC)

Previous referendums in B.C., like those on the electoral system in 2005 and 2009 or on the harmonized sale tax in 2011, all had a voter turnout of more than 50 per cent.

However, there is no minimum voter participation threshold for any referendum.

The government has come under criticism for the way the ballot and its questions are structured. University of the Fraser Valley political science professor Hamish Telford said he questions the amount of engagement undertaken to promote the referendum.

George Heyman, MLA for Vancouver-Fairview and the Environment Minister also participated in Sunday's day of action.

With files from Clare Henning and the Canadian Press.