He is still a member of the Coalition but does not attend the Nationals party room meetings because he cannot abide the leadership of Mr McCormack.
After the failed coup, the position of deputy speaker became vacant when  incumbent Kevin Hogan, a McCormack supporter, was promoted to the ministry.
Mr McCormack, in consultation with Scott Morrison, chose Damian Drum as the new Deputy Speaker and the government wrongly assumed the Parliament would rubber stamp the choice in a secret ballot to be held after Question Time on Monday.
It was only during that Question Time that Labor, using back channels, made the proposal to Mr O’Brien, after both Mr Gillespie and Mr O’Dowd had declined.
Mr Joyce had urged Mr O’Dowd to run and was involved in then sounding out Mr O’Brien.
Labor did not know whether he would accept. No one did. So Mr Burke waited until Mr O’Brien left the chamber after Question Time to nominate him. Because he was absent, he automatically entered the ballot.
Like the rest of the Parliament, Burke and leader Anthony Albanese only learned Mr O’Brien would accept when he returned and told the House he accepted the nomination.
Four other Nationals Mr Joyce, Mr Gillespie, Mr O’Dowd and George Christensen voted with Labor and the crossbench to humiliate Mr McCormack and, by extension, Mr Morrison, by 75 votes to 67 votes.
Regardless, Mr McCormack agreed to fulfil a visit to Mr O’Brien’s electorate of Wide bay on Friday for what was an awkward joint appearance.
Mr O’Brien, who boosted his salary by $42,000 by truing against his side,  assured his voters he was still a member of the government but Mr McCormack was not his leader.
“I support Michael McCormack as my deputy Prime Minister,” he said.
“My leader is Scott Morrison, the Prime Minister who I work closely with.”
Asked why he tried to topple the man standing next to him, Mr O’Brien hid behind the supposed confidentiality of the party room and its ballot process.
He was unperturbed at suggestions he could be expelled from the LNP.
“I put myself to the people of Wide Bay on the 18th of May last year,” he said.
“When they took that ballot paper it said ‘Llew O’Brien LNP’. That’s what they bought, that’s what they got, that’s what they’ve still got.”