Liberals to launch campaign next Sunday

The Liberal Party will launch its campaign next Sunday, as the party attacked Labor's show of unity.

Prime Minister Scott Morrison will officially launch his campaign on Mothers Day. (AAP)

The Liberal Party will officially launch its election campaign next Sunday.

Labor held its launch on Sunday in Brisbane, with former prime ministers Kevin Rudd and Julia Gillard seated side-by-side despite years of enmity.

But coalition campaign spokesman Simon Birmingham said their act of party unity fooled nobody.

"The only thing that Kevin Rudd and Julia Gillard could agree upon was that they didn't trust Bill Shorten," Mr Birmingham told reporters in Adelaide on Sunday.

Mr Birmingham, however, didn't reveal if the coalition would display their own show of unity with former prime ministers Malcolm Turnbull and Tony Abbott.

The Liberal Party's launch will instead heavily focus on the creation of jobs and a plan for the future that "doesn't rely on taxing Australians more".

Mr Birmingham also attacked Labor for not clarifying to voters the costs of their policies.

Labor leader Bill Shorten said he would reveal his campaign policy costings at the end of the coming week, well before the May 18 election.

The Liberal Party stopped short of revealing theirs, saying voters can look at their 2019-20 budget, handed down last month.

"Australians can have complete confidence that our costings will match up with our budget, which was verified independently by [the Pre-election Economic and Fiscal Outlook]", Mr Birmingham said.