Countless interviews, a lengthy press conference, a resignation speech in the Senate – and Cory Bernardi still can't convince some people why he quit the Liberal Party.

The newly minted independent clashed with Today host Karl Stefanovic on Wednesday, challenged over what took him so long to "man up" and announce his plans to form a new Australian Conservatives party.

Stefanovic's questions echoed those of many in Canberra and Australia this week, as Senator Bernardi was unable to explain personality or policy differences that led him to leave the Liberal Party after 30 years, including 10 years in the Senate.

"I've come to the realisation that party politics, major party politics, is failing the Australian people and you just have to look at the evidence all around us," he said.