"Let's be really clear here. There is no way that you can do a preference deal without me signing off on it," Mr Shorten told the Nine Network on Sunday.
He said there was one question that has not been satisfactorily answered by Prime Minister Scott Morrison when giving preferences to Mr Palmer and his Nationals coalition partner giving their preferences to One Nation.
"What have they promised Pauline Hanson and Clive Palmer?" Mr Shorten asks.
Deputy Labor Leader Tanya Plibersek played down Labor's approach to Mr Palmer.
"Look, I don't think a couple of SMSs is what you'd call a formal negotiation," she told ABC television.
"Bill's made it very clear that we would never have had a formal arrangement with Clive Palmer while he owes his workers $70 million."
She noted Mr Palmer told his own candidates he would probably spend $70 million promoting himself on the side of every bus and billboard around Australia.
[The full story is available on the podcast above]