Half of the Conservative leadership candidates have "no credibility whatsoever", according to former international development secretary Priti Patel.
The European Research Group member said she did not trust anyone from the current cabinet to take on the role of Tory leader and Prime Minister.
"At a time like this we cannot have a circus carrying on. We need a strong leader," she told talkRADIO's Julia Hartley-Brewer.
"We need a radical change, a leader who can restore trust across the country, deliver Brexit, but who will also deliver for our country. Raise our standards in the world once again. We have become a laughing stock."
Five of the 10 candidates vying for the top job are cabinet ministers: Rory Stewart, Jeremy Hunt, Matt Hancock, Sajid Javid and Michael Gove.
Today, MPs will be voting on who they want to take on the role, and each candidate must secure at least 17 votes or be eliminated from the process.
Ms Patel continued: "The country and parliamentarians and Parliament and everyone is just sick to death of what has gone on over the last three years.
"We have had three years of dithering and trying to be all things to all people on Brexit, and that is the reason we are in the mess we are in."
The politician is backing bookies' favourite Boris Johnson to become next Tory leader.
"Why Boris? We have to get back to our winning ways. We have to be in tune with the hopes and desperations of Britain's hard-working, law-abiding majority."
She congratulated him on his resounding first round victory on Twitter.
She wrote: "Congratulations Boris Johnson on winning 114 votes in the first ballot with MPs".