Senators should be banned from serving as ministers, corporate donations should be outlawed and all perks should end when politicians leave office, according to outspoken Liberal Party senator Cory Bernardi.

But Senator Bernardi, who resigned from the Coalition front bench in 2012 amid widespread furore over comments he made that same-sex marriage would lead to legalised polygamy and bestiality, refused to rule out returning to the front bench himself.

Senator Cory Bernardi at the National Press Club on Thursday. Credit:Jeffrey Chan

In a speech decrying the mediocrity of many of his political colleagues, the South Australian senator said too many politicianswere risk-averse and lacked conviction.

"Some elected officials view politics as a career rather than a temporary duty, fuelling the perception that it becomes more about self-interest than national interest," Senator Bernardi told the National Press Club.