Chief Minister Katy Gallagher has predicted Zed Seselja will be the next Liberal Senator for the ACT.
Speaking before Mr Seselja confirmed Fairfax's reports he would challenge Senator Humphries for preselection, Ms Gallagher said she didn’t believe Mr Seselja would be challenging unless he had the numbers.
Ms Gallagher said Mr Seselja’s position as Liberal Leader in the ACT Assembly was now untenable.
“I doubt very much that Mr Seselja would be nominating for something he is not going to win ... within the Liberal Party,” Ms Gallagher said.
“I mean he’s not silly, he’s been doing the numbers over a couple of years now from my understanding. From everything people tell me – and the Liberal Party has numbers, has factions – he will deliver if he nominates for the position. So I would say his position as leader is untenable.”
Ms Gallagher criticised Mr Seselja for looking to leave the Assembly just three months after being elected for the first time as an MLA for the southern electorate of Brindabella.
Mr Seselja was previously an MLA for the central electorate of Molonglo.
“He’s represented the people of Tuggeranong for three months and he’s heading out of there,” Ms Gallagher said.
“It seems a little bit strange to me. He represented the people of Molonglo until it was better to represent the people of Brindabella and now it looks like representing the Senate is the way to go.”
Federal Labor MP Andrew Leigh said Mr Seselja's challenge was another sign of how Tony Abbott was radicalising the Liberal Party.
"Senator Humphries is well known as a Liberal moderate while Mr Seselja is a close ally of Mr Abbott," he said.
"Liberal Party preselectors should be looking to the candidate that better fits Canberra's moderate ideology, not the person who will shore up Mr Abbott's leadership numbers."
Greens' Senate candidate for the ACT Simon Sheikh described the preselection challenge as the beginning of a brawl inside the Canberra Liberals.
"Canberrans know that whoever the candidate is on the Liberal Party side, Tony Abbott will continue to sell out Canberra with his policies that would push our local economy into recession," he said.
"Neither candidate has shown their ability to oppose Tony Abbott's job cuts that would hurt families across the ACT.
"Both Gary Humphries and Zed Seselja take the ACT for granted, despite the fact that we live in the most marginal Senate seat in the country.
"This brawl shows that both Gary Humphries and Zed Seseljia care more about their own jobs than they do about the jobs of Canberra's families.
"While they are brawling over a job by Tony Abbott's side, I'll be out fighting to protect the jobs that are so important to our local community."