ROME — Italy on Friday edged closer to holding an election as early as this fall that could move the country further to the right, with anti-migrant Deputy Premier Matteo Salvini already unofficially campaigning for the premiership and declaring it makes ‘‘no sense’’ to keep alive the feuding populist coalition government.

Milan’s stock market plunged by 2.4 percent, and borrowing costs on Italian debt — an indication of nervous investors — jumped higher after Salvini’s surprise announcement Thursday night that his right-wing League party no longer would support Premier Giuseppe Conte.

The 14-month-old coalition’s senior member is the anti-establishment 5-Star Movement headed by rival Deputy Premier Luigi Di Maio, who has sparred with Salvini increasingly on key policy issues.


Although President Sergio Mattarella hasn’t indicated if or when he will dissolve Parliament, a condition for early elections, a return to the ballot box could come as soon as late October, politicians and analysts calculated, after a mandatory campaign period.

Any electoral campaign this fall would play out just as the Italian government hammers out a new budget to meet European Union rules and deadlines. There already are concerns Italy might have to raise value-added tax since it’s reluctant to cut expenditures that please voter constituencies.

Conte has demanded Salvini, who is also interior minister, lay out his reasons in Parliament for refusing to continue to back the government he helped form after 2018’s elections brought populists to power for the first time in Italy.

Salvini must ‘‘explain to the country and justify to the voters who believed in the prospect of change the reasons that led him to interrupt ahead of time, abruptly, the work of the government,’’ Conte said.

For a year now, the League’s popularity has soared in opinion polls and in local and regional balloting, as well as the European Parliament elections earlier this year.


Those soundings have also shown a plunge in support for the oft-bickering 5-Star Movement, whose sometime left-leaning platform has kept the League from pulling the government further to the right.

‘‘I don’t look at the opinion polls,’’ Salvini said Friday during an appearance in Termoli, a seaside town in the south. ‘‘I said ‘stop’ because when a government, instead of doing things, blocks them, it makes no more sense’’ to continue.

Di Maio predicted Salvini’s abrupt yanking of his support would backfire at the ballot box.

‘‘When you take the country for a ride, sooner or later the bill arrives, sooner or later you pay the consequences,’’ the Italian news agency ANSA quoted Di Maio as saying in a written statement.

The government is obliged to resign if it loses a confidence vote.

The Democrats, Italy’s largest opposition party, are creeping up in opinion polls at the apparent expense of the 5-Stars, but they lag far behind the League.

Legislators have just started their summer vacation and it’s unclear when they might be called back into session to hold debate and a vote.

Lawmakers ‘‘should move their rear ends and come to Parliament, if need be, even next week, because millions of Italians are also working the next week, and the week after,’’ Salvini told a sea of cheering supporters Thursday night in Pescara, a small city on the Adriatic.

Although he has spent much of the last few weeks at the beach, Salvini frequently depicts himself as the champion of the working class.


Salvini regularly rails against EU budget rigor, insisting that more state spending on infrastructure will get Italy’s long-stagnant economy growing again. His pro-Russia party also clashes with Brussels’ sanctions against Moscow over its annexation of Crimea from Ukraine.

Italian prosecutors are investigating if a close Salvini associate had illegally schemed to obtain Russian funds for the League. Salvini contends he’s never taken money from Russians.