The prime minister laid out what he said was a stark choice, in an animated speech to the party faithful at the Liberal federal council in Sydney on Saturday.

"Our values are timeless because they are based on freedom," Mr Turnbull said.

"They are values which say that government's job is to enable you to do your best. To realise your dreams, to get your business going, to get your career going, to see your kids getting ahead and getting a great education."

He signalled the party will go after Bill Shorten, with attack ads highlighting Labor's policies on border protection and taxation.

"A Labor platform of higher taxes on everyone - individuals, businesses, trusts, investment, property - does anyone imagine that that will have any result other than less investment and less employment?" Mr Turnbull said.

The Liberals will also run ads showing how many Labor MPs and party members want to change government policies on refugee boat arrivals and mandatory detention.

The coalition's strategy will get its first test in the Super Saturday by-elections on July 28, but Mr Turnbull played down the government's chances.

"The last time the government won a by-election from the opposition was 100 years ago," he told reporters.

"We fight every election to win, but you have to be realistic."

Former prime minister John Howard said history shows Labor's primary vote is too low and it wasn't in the strong position that oppositions had in 1996, 2007 and 2013.

"On each of those occasions the primary vote of the winning party was in the middle 40s for a consistent period of six or 12 months before the election," Mr Howard said on Saturday.

"The Labor primary vote has been stuck below 40 per cent for a very long time.

"That is a salutary reminder, although there may be irritation and disappointment with us, there is no enthusiasm for the replacement."

Party president Nick Greiner used a speech on Friday to tell Liberals to lock in behind Mr Turnbull instead of infighting.

Australian Associated Press