The Greens will announce their Bass candidate within a fortnight, while the Liberals will announce who will challenge Sid Sidebottom in Braddon in the same time frame.

Retiring MPs have been asked to give their valedictory speeches in the next couple of weeks, leading to suggestions the federal election will be called before Parliament resumes on August 24.

Tasmanian Liberal Party president Sam McQuestin said three of the party's candidates had been secured, while the other two were still being selected.

The confirmed candidates are:

Steve Titmus (Liberal) and Geoff Lyons (Labor) in Bass.

Julie Collins (Labor incumbent) and Jane Howlett (Liberal) in Franklin.

Dick Adams (Labor incumbent) and Eric Hutchinson (Liberal) in Lyons.

Sid Sidebottom (Labor incumbent) in Braddon.

Jonathan Jackson (Labor) in Denison.

Mr McQuestin said he had had a number of conversations with former Braddon MHA Brett Whiteley about making the shift to federal politics, but the preselection process was continuing.

With the retirement of Labor MHR Duncan Kerr, Mr McQuestin said there was an opportunity for the Liberals to gain some traction in Denison.

But he acknowledged the strength of the Labor and Green vote in the electorate would be difficult to overcome.

Tasmanian Greens federal election campaign manager Sancia Colgrave said Denison was on the Greens' national radar as a chance to get a seat.

"It's one we're paying the closest attention to," she said.

Ms Colgrave said the Greens' preference deals - likely to be crucial in determining who wins in Bass - would be done at a national level.