Craig Kelly promises to support PM on critical votes until election after joining up with Clive Palmer

The maverick, who quit the Liberal Party in February to become an independent, announced on Monday he would lead Clive Palmer's United Australia Party into the federal election and claims it will be "a major political force".

Mr Kelly said the party, which failed to win a seat at the last election despite big spending, "will be fighting to end the lockdowns and offer an alternate approach to the current mayhem and destruction that the Labor and Liberal parties have jointly created".

The MP told the Leader, for as long as this Parliament ran, he would continue to guarantee supply and support the Morrison government in confidence votes, keeping faith with voters in Hughes who elected him.

Mr Kelly said he decided to join up with Mr Palmer because of "the firepower and resources" to ensure alternative expert opinion on the pandemic and lockdown measures could be debated.

He claimed Australians were being denied "a second opinion from doctors who have been silenced".

"We will be a major force in politics," he said in a statement.

"The United Australia Party will run candidates in all 151 lower house seats across the length and breadth of the nation, and in the Senate."

However, questions over his role quickly emerged.

Mr Kelly told a media conference he would be the party's official leader and set its policies while Mr Palmer would continue as the party's chairman.

A spokesman for Mr Palmer said Mr Kelly would have "input" into policy, which would be determined by the party's executive, of which Mr Kelly would be a member.

Mr Kelly quit the Liberal Party in February after refusing to stop promoting COVID-19 treatments that were contrary to federal health views.

"My intention at the time was to contest the next election as a maverick independent in my southern Sydney seat - and use Don Chipp's line of "Keeping the bastards honest"," he said on Monday.

"However, over those past six months, I have witnessed the very fabric of our society unravelling.

"With endless authoritarian lockdowns - censorship of expert opinion - the emergence of a Biomedical Security State - our state borders shut contrary to the vision of our Federation, and the freedoms that were the birthright of every Australian stolen with vague promises of them returning if we submit to coercive experimental medical treatment - I no longer recognise the country grew up in, and I fear for our nation's future if we continue on the current path.

"And this is all happening on my watch. Someone must lead a fightback."