Ben Carroll had hoped to quietly rise to the top job. Instead, he became Victoria’s 50th premier after 48 hours of heated confrontations and shouting matches, all as the public watched on.

It was his first confrontation against the premier, and he emerged from it relatively unscathed.

Unlike many leadership challengers, Carroll did not openly campaign against Allan. He only agreed to stand after a cross-factional delegation of MPs told him Allan had lost the confidence of the caucus and urged him to nominate.

That allowed him to reconcile his change in position from just six weeks earlier, when he looked Allan in the eyes and told her he wouldn’t challenge her, adding that he wanted his daughter to see a woman elected premier in her own right.

“The circumstances changed. Yesterday morning, I was approached by a delegation who asked me to stand for leader. This delegation had already visited the premier and informed her that they wanted change. I’m going to be that change,” he said on Tuesday.

Initially, Allan refused to concede defeat. On Monday, she publicly declared she would fight for the leadership and even formally nominated herself with the party’s state secretary, a step she was not required to take at that stage.

Had she persisted, Labor would have faced a bruising six-week leadership contest, with the outcome determined by both a caucus vote and a ballot of party members. It would have prolonged - and made even more public – the government’s internal infighting just months before an election.

But by Tuesday morning, with the numbers decisively against her, Allan resigned. She insisted she believed she could have won a leadership ballot but said standing aside was “the right thing” for Labor and for Victorians, because she was a “team player”.

That should have cleared the way for Carroll to be elected unopposed. Instead, the chaos escalated.

The attorney general, Sonya Kilkenny, one of Allan’s closest allies, unexpectedly nominated for the leadership, triggering a second confrontation. Raised voices from inside the caucus meeting could be heard from parliament’s hallways as MPs argued over the move.

The nomination stunned many in the room because Allan was among the 15 MPs who signed Kilkenny’s nomination papers. It directly contradicted her comments only an hour earlier that she wanted to avoid a prolonged and damaging contest.

At the same time, Steve Dimopoulos challenged Carroll’s preferred deputy, Gabrielle Williams.

One MP described the moves as Allan trying to “blow up the joint on her way out”. But it was more likely an attempt by her supporters to extract concessions from the incoming leader.

Or, as one MP put it, their colleagues were simply “scrambling for the scraps”. This, despite what another source said was Carroll’s assurance prior to the meeting that no MPs would “lose out” under his leadership.

Ultimately, five minutes before the caucus meeting concluded at midday, Kilkenny withdrew her nomination. Carroll was elected unanimously, and Williams won the vote for deputy.

One MP said they did not expect Carroll to respond with “recriminations” as it was “too risky for everyone” seeking unity months out from an election.

Another Labor source said if Carroll gave Allan supporters “a stake in the success” of the government (read: cabinet positions), it would stop them from “becoming angry and isolated” (read: leaking and undermining).

But the main challenge for Carroll now is to convince voters that while he inherits Allan’s government he will not simply continue it. This was the mistake Allan made when taking over from Andrews.

In announcing a royal commission into the construction sector “as soon as possible” and immediately boosting the anti-corruption watchdog’s powers, he has taken the first step in charting a new course.

The move is designed to confront Labor’s most politically damaging issue – and is a step Allan had refused to take. But it is not without risk. A royal commission running during an election campaign is almost certain to generate damaging headlines – though Allan and Andrews are more likely to bear the brunt.

Carroll has also sought to project a message of fiscal restraint, given Labor’s debt is forecast to reach almost $200bn in coming years. He said his first job at his local Kmart taught him the “value of a dollar”.

“That’s why I understand why Victorians are concerned about government spending. Every dollar my government spends will be treated with respect,” he said.

He also flagged plans to mend the relationship with the business community, who will be watching closely to see if he maintains Allan’s flagship legislation protecting the right to work from home two days a week. His supporters say tax concessions are more likely.

Questions also remain over the future of the $34.5bn Suburban Rail Loop. Carroll, whose northern suburbs electorate does not directly benefit from the eastern section currently under way and who is understood to have privately questioned the project, has promised “more announcements” on its future.

One option being canvassed is bringing forward plans for the western section between Werribee and Melbourne airport, though it’s unclear how this reconciles with Carroll’s plan for fiscal responsibility.

On Tuesday afternoon, MPs said they felt sad, hopeful, “gross” and like they had “[woken] up from a bad dream”. But all agreed the hard work was just beginning.

• Benita Kolovos is Guardian Australia’s Victorian state correspondent