Australia’s governing coalition has ruled out calling an early election despite a crushing by-election defeat in a historically safe seat that left it without the lower house majority in parliament needed to ensure that laws are passed.

Opposition parties are already rallying support for a no-confidence vote that will test whether the Liberal Party-Nationals alliance, now reliant on cross-benchers, has the numbers to continue. However, deputy leader Josh Frydenberg denied the government faced a struggle for survival.

“We are not going to be in a situation of chaos, we are going to be in a new world without a clear majority on the floor of the house,” he said in an interview with Sky News. “That being said, history shows that governments without a clear majority can run for a number of years.”

The Sydney seat of Wentworth had been held by conservatives for 117 years until it was claimed by independent Dr Kerryn Phelps in Saturday’s by-election with a 19% swing. The seat was vacated by former PM Malcolm Turnbull after he was ousted as Liberal leader in August in a coup by his own party.

Postal votes are still being counted, but Phelps has an unassailable lead with about 51% of the vote after the distribution of preferences; Liberal candidate Dave Sharma has 49%. In the 2016 general election Turnbull had a 17.7% edge over his nearest rival, giving him 70% of all votes polled.

Protest vote

A former head of the Australian Medical Association and local councilor, Phelps owes her victory to a protest vote over the shoddy treatment of Turnbull. Opinion polls showed that traditional Liberal voters were also unhappy at efforts to shift the party’s ideology further toward the right.

The government now has 75 seats in the 150-member house, compared with 69 for the main opposition Labor Party. There are six cross-benchers, including three independent legislators, who hold the balance of power.

In the Senate, or upper house, the government controls only 31 of the 76 seats, forcing it to again deal with powerbrokers. Labor has 26 senators and the remaining 10 seats are held by independents and small factions.

All six cross-benchers have offered the government a lifeline by pledging support in the event of a no-confidence motion by Labor, which requires only a simple majority vote. Phelps said she believes “all governments should go full term unless there are exceptional circumstances”.

An election must be called by May next year, and Prime Minister Scott Morrison will wait until the last possible date to rebuild after Saturday’s loss. But cross-benchers will demand tradeoffs in return for their votes.

Climate change, asylum-seekers key issues

Greens legislator Adam Brandt said on Monday that he won’t back the coalition’s bills unless it closes coal-fired power stations and commits to climate change policies, which was a key issue for the Wentworth voters.

“If you don’t have a plan to get off coal and onto renewables, voters will punish you. I won’t be offering support to the government,” he said.

Another cross-bencher, Cathy McGowan, wants asylum-seekers held in detention camps on Nauru to be transferred to Australia, as do Brandt and Phelps. This was another leading issue cited in Saturday’s poll.

The by-election defeat may not be a good indicator on broader political trends for the coalition, as Wentworth’s voters are more engaged and better informed than typical electorates. But the fact that the government could not retain one of its safest seats suggests it may be in strife in 2019.

Morrison has limited room to turn the coalition’s fortunes around, as the loss has dented his own credibility at a time when he is trying to reconcile the Liberal’s two camps. A swing of a similar magnitude to Wentworth on a national level, which now seems possible, would decimate the coalition.

However, the news is no better for Labor, which suffered a 6.2% swing in its Wentworth vote through candidate Tim Murray. Some commentators believe the poll served as a protest vote against both major parties and could be the start of a grassroots push to put all politicians on notice.

“Representatives connected to their communities, with a will to serve them, can take seats away from Labor too, and from the Nationals,”  columnist Katherine Murphy wrote on The Guardian’s website.

“There’s an earthquake going on in Australian politics. So far it’s just a rumble, but if the incumbents don’t hear the rumble, and start to change things up, make no mistake: the rumble will become a roar,” Murphy said.