Lyle Shelton has stepped down as the head of of the Australian Christian Lobby to pursue a career in federal politics.

Shelton, a leading protagonist in the campaign against marriage equality, will move from Canberra to his home state of Queensland to prepare for the next federal election.

There is speculation he will be joining Liberal defector Cory Bernardi’s Australian Conservatives party.

Shelton said he was not abandoning his campaign to promote conservative values in Australia.

“Last year, during the marriage campaign, I felt very much drawn to the political side of things, to the partisan side of politics,” he said.

“I’m not leaving the battle for the values that you and I hold dear – just simply going to a different part of the battlefield.”

Shelton said he would make a specific announcement about his run for federal parliament in the coming days. He is expected to nominate for a lower house seat or a Senate spot, in a state already crowded with conservative candidates and where One Nation’s anti-major party vote is well-established.

Shelton’s former chief of staff, Martyn Iles, will take over as managing director of the ACL.

“There’s never been more pressure on people of faith and on the church simply for living out our timeless convictions,” Iles said.

“Therefore there’s never been a more crucial time in history in Australia for the church and for Christian people to continue to engage with law and with politics and with culture.”

Shelton and Bernardi were closely aligned in the ultimately unsuccessful campaign against marriage equality in Australia.

Of the Australians who returned a ballot in the postal survey, 61.6 per cent were in favour of reforming the Marriage Act to allow same-sex couples to wed.

South Australian senator Bernardi defected from the Liberal party in 2016 to form the Australian Conservatives.

The party has never won a parliamentary seat at an election. In addition to Bernardi, it has two members in the South Australian upper house (former members of the now-defunct Family First party), and one member of the Victorian upper house (a former member of the Democratic Labour party).

– Australian Associated Press contributed to this report