South Australian senator Cory Bernardi, who broke away from the Liberals to form his own, now-deregistered conservative party says he will quit politics at the end of the year.

Key points: Cory Bernardi will end his 13-year political career at the end of the year

Cory Bernardi will end his 13-year political career at the end of the year He maintains he did not go "too hard" when speaking out against same-sex marriage

He maintains he did not go "too hard" when speaking out against same-sex marriage His seat in the Senate will go to a Liberal candidate, as he was one when he was elected in 2016

The now-independent senator says he is leaving politics with his integrity intact and very few regrets.

"The timing is right, I just don't want to go back to it next year — I feel in a very happy and comfortable place," Senator Bernardi said on Sky News.

"Other people will define it [my career] how they want.

"If nothing else I opened up lots of conversations, I remained true to my values and principles. People will make judgments about whether they were right or wrong.

"One of the great things is my integrity is intact. I feel very comfortable with who I am and what I have spoken about and if I have regrets, there are very few."

Senator Bernardi, who has been in Parliament for 13 years, has been an outspoken critic of same-sex marriage and climate change but said he did not feel he overstepped on either issue, particularly same-sex marriage.

"I don't think I went too hard on any issue — in the same-sex marriage debate I spoke truth to many people's concerns."

He said critics twisted and distorted his words for their own purposes.

He quit the Liberal Party in 2017 to form the Australian Conservatives, arguing the Coalition under Malcolm Turnbull was straying from the conservative values upon which it had been founded.

But his party struggled to attract support at this year's federal election where new Prime Minister Scott Morrison led the Coalition to a slim majority government.

Senator Bernardi announced in June that a "lack of political success" and money meant he was deregistering the Australian Conservatives.

Senator Bernardi secured a six-year Senate term when he was elected in 2016 and his resignation will trigger a casual vacancy.

Despite him breaking away from the Liberals, that party will still have claim to the seat, as Senator Bernardi was a Liberal member when elected.