Fracking will be banned in Victoria until 2020 if the Liberal-National coalition wins power again.
Coal seam gas mining is on hold in Victoria while a parliamentary inquiry examines the practice.
But the opposition wants it banned until 2020 to give the state time to assess its impact and implement law changes.
"The work has not been done, we don't have the regulatory framework to enable an industry to develop," Nationals leader Peter Walsh told reporters on Monday.
An Auditor-General's report into coal seam gas found there were major problems with applying current earth resources regulations to unconventional gas mining.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
"The findings of the Auditor-General support our view that the case for an expansion of the commercial unconventional gas industry in Victoria has not been made," Liberal leader Matthew Guy said.
In a rare show of candidate unity, the rival Liberal and National candidates for two western Victorian by-elections posed for photographs together to endorse the policy.
Victorian Energy and Resources Minister Lily D'Ambrosio said it was Labor who first called for a moratorium in 2012 when it was clear there were gaps in scientific knowledge.
She said the parliamentary inquiry into coal seam gas was relying on science and consultation.
"The government will consider the recommendations when the report is handed down in December and will not be making knee-jerk decisions because there is a by-election in western Victoria," Ms D'Ambrosio said.
Victorian Greens leader Greg Barber said the coalition policy would leave communities with more uncertainty and renewed calls for a permanent ban.
"What the coalition is saying today is they will go to the 2018 election with a policy of a two year moratorium," Greg Barber said.
Australian Petroleum Production and Exploration Association chief operating officer Paul Fennelly said onshore gas could drive jobs and economic development in regional areas.
"The experience of Queensland also shows that onshore gas can successfully coexist with farming and other land uses," he said.
