Dr Glasson was the first to publicly put his hand up for the upper house seat.

The practisng ophthalmologist shrank then-prime minister Kevin Rudd's margin in Griffith from 8.5 to just 3.01 per cent at the 2013 federal election, before losing the subsequent byelection, brought on by Mr Rudd's retirement, to Labor's Terri Butler.

On Saturday morning, Dr Glasson texted Fairfax Media from Stradbroke Island, where he was attending an Institute of Urban Indigenous Health board meeting, to confirm his candidacy.

"As of last night, I have made a decision to stand as a candidate for the upcoming ballot to fill the casual vacancy in the Senate," he said.

Senator Mason announced to his party room in Canberra on Tuesday that he would leave the Senate before the expiration of his term, which was due to end on June 30, 2017.

HIs retirement allows the LNP to appoint a new senator without the need for a byelection.

State Opposition Leader Lawrence Springborg said he would not be throwing his support behind any LNP Senate candidate prior to the nomination.

"It is a matter for the state councillors of the LNP," he said.

"The role of a Senate candidate is to be selected from within the broad support of the LNP and then, ultimately, to win the support of Queenslanders.

"It is not for the leader of the LNP's state parliamentary wing to be anointing candidates in that circumstance.

"…It is up to grassroots members. That is the view I've always had, that's the view I have today."

Dr Glasson revealed his interest in the position on Tuesday, when Fairfax Media informed him of Senator Mason's announcement.

On Friday, the LNP formally opened nominations, which will close on April 8.

The successful candidate will be decided when the LNP state council meets at the Brisbane Convention and Exhibition Centre on May 16.