Italian Interior Minister Matteo Salvini said on Friday that parliamentarians would have "to get off their bums" and return to Parliament for a no-confidence vote after his far-right League party announced it would submit a corresponding motion to the Senate.
League senators sought a confidence vote in Parliament on Conte's government that the premier appeared destined to lose, without Salvini's support.
An early election may benefit Salvini, with recent opinion polls putting his League party ahead, leaving open the possibility that it could govern in alliance with another, smaller far-right party, Fratelli d'Italia.
"Salvini came to tell me that the League intends to interrupt this experience in government and to call for a vote in order to capitalize on the consensus his party now enjoys", Conte told reporters at a nationally televised press conference.
The governing two parties have been at odds over a host of policy issues but tensions spiraled Wednesday after the Senate rejected a move by 5-Star to kill a EU-funded high-speed rail link with neighboring France.
Salvini's anti-migrant, anti-NGO stance is credited with the League's surge in popularity.
The decision to call an election rests with President Sergio Mattarella, now on holiday in Sardinia, who is known to oppose polls in October.More news: Body found in search for missing Irish teenager Nora Quoirin
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Italian media has reported that Salvini, in earlier talks with Conte, set conditions for staying in the coalition - including the resignation of the transport, defence and economy ministers, who have resisted his projects and policies.
5-Star was the largest party at last year's elections but it has struggled since the government was formed, while Salvini has prospered thanks to his popular hard line on immigration and a charismatic and informal "man of the people" public image.
Yet major impediments remain as the timing for elections in August summer period as well as scheduled preparatory works for the 2020 budget in September are likely to hinder the prospect of elections.
Both houses of parliament are now on recess for the holidays and are not due back until September.
Salvini, who effectively triggered the crisis on Thursday by declaring the ruling coalition unworkable, accused his critics of scheming to save their posts and keep him from power.
This would supposedly be between a new M5S leadership supported by the centre-left Democrat Party of former premier Matteo Renzi plus lawmakers who fear losing their seats in a snap poll.
The 5-Star Movement's fortunes have sunk conversely, from almost 33% of the vote in the national elections, giving it more seats in parliament than its partners, to just 17% in the European elections.
"This government's only option is to let Italians have their say" by calling elections, it added.