SYDNEY, Australia — Prime Minister Malcolm Turnbull of Australia has accomplished a dubious feat: for the 30th straight time, an opinion poll placed his governing Liberal Party behind the opposition, intensifying pressure on the embattled leader as he confronts a tide of stubborn scandals.

The Newspoll, one of the country’s most respected political polls, was the same survey that Mr. Turnbull used to justify forcing his predecessor, Tony Abbott, from office in 2015.

Mr. Turnbull’s poor showing in the latest poll, released Sunday, marks what experts describe as a rare moment in the country’s political history: The government hasn’t won a single Newspoll since the day of its election two and a half years ago.

Faced with the troublesome poll results, Mr. Turnbull said he was meeting expectations on another front: the success of his policies.