Pauline Hanson has denied One Nation is now a divided party, while claiming her colleague Brian Burston had “sold himself out” by defying her to back the company tax cuts.

At a joint press conference with Peter Georgiou on Thursday, Senator Hanson claimed One Nation was united despite Senator Burston’s decision to support the government’s key economic policy.

“We are not a loose alliance, we are a party,” she said.

In farcical scenes, Senator Hanson left the press conference while Senator Georgiou remained to field more questions.

Asked how he could claim One Nation was united when his boss had just walked off, the WA senator replied, “Actually I didn’t realise she walked away,” before also leaving the press conference.

The One Nation leader, who last week backed out of a deal with the government to back the tax package, said Senator Burston had “sold himself out”.

Despite trying to paper over cracks emerging within the three-vote bloc, Senator Hanson also appeared to cast doubt over Senator Burston’s preselection.

“Just because you’re a senator for New South Wales doesn’t mean to say you have automatic … top of the ticket,” she said.

“It’s a preselection process that is yet to be finalised. It’s like all the other major parties.”

While Senator Burston’s position within One Nation now appears in doubt, Senator Hanson said she hoped to speak with him in the next few days.

I know he hasn’t been well, I have tried to make contact with him but because of our schedules, we haven’t been able to.

“He is a member of the party. He’s still a representative of One Nation in the Parliament.”

Senator Burston’s comments, reported by The Australian on Thursday morning, give the government an extra vote for its company tax cuts package.

But without the support of the three-vote One Nation bloc, as well as the as yet unconvinced two Centre Alliance senators, the package is unlikely to pass in the Senate in the next parliamentary session.

Senator Burston told The Australian he felt compelled to honour the deal that One Nation had made with the government.

That deal included significant changes to the Petroleum Resource Rent Tax and an apprenticeships scheme.

He claimed he was not consulted over the move, and suggested Senator Hanson had likely changed her position due to the upcoming Longman byelection.

But Senator Hanson claimed Senator Burston told her he backed the decision to oppose the tax cuts in a phone conversation last Monday.

The divisions follow Senator Hanson’s decision to boot Fraser Anning from the party last year. He had refused to stand aside so her close ally Malcolm Roberts, who lost his position over citizenship, could return to Parliament.

Last week, Senator Burston was stripped of his position as party whip, the ABC reported.

Finance Minister Mathias Cormann seized on Senator Burston’s support for the tax package on Thursday.

“The government has never walked away from the agreement we have reached [with One Nation]. I have said consistently that the government remains 100 per cent committed to the agreement we reached with Senator Hanson and the One Nation team,” he said.

“The government is very appreciative of the fact that Senator Burston has announced he will stick to the agreement that was reached.”

Labor remains unconvinced by Senator Hanson’s change of heart, saying it expects she will eventually vote for the package.