An Italian policeman looks at an electoral poster at a polling station in Rome.
Italy's national election produced no outright victor on Sunday, according to exit polls that pointed to political gridlock for the euro zone's third-largest economy and showed voters backing anti-establishment and far-right parties in record numbers.
The League has overtaken former Prime Minister Silvio Berlusconi's Forza Italy (Go Italy!) party as the largest in the coalition.
The Five Star Movement, once laughed off as merely a protest party, is expected to emerge as the single biggest party, with up to 33% of the vote.
Salvini insisted in a news conference that his center-right coalition has earned "the right and duty to govern" and he was not interested in any new "strange coalitions".
"The European Union is having a bad evening", French far-right leader Marine Le Pen tweeted. His party, which campaigned on a fiercely anti-migrant ticket, looked set to win more than 17 percent of the vote against just 4 percent at the last national election in 2013.
In Brussels, a European Commission spokesman said it was confident a stable administration could be formed, "and in the meantime Italy has a government with whom we are working closely".
With polls showing the centre-left trailing, Democratic leader Matteo Renzi and the current premier, Paolo Gentiloni, spent the final days of the campaign warning that the only way to guard against a turn to populists and extremists was to vote for the Democrats. "The populists have won and the Democratic Party has lost", Andrea Marcucci, one of the party's lawmakers in the outgoing parliament, wrote on his Facebook page.
Observers say none of the blocs will likely gain more than half of the seats on their own and that the center-right bloc is expected to lead talks to form a coalition government.
The other would be a minority Five Star government, which could prove highly unstable. A new election could also be held.
The 5-Star Movement, led by 31-year-old Di Maio, has been particularly successful at tapping into the disaffection in the underdeveloped south and has promised a monthly universal wage of up to 780 euros ($960) for the poor.
The party appeared to have gained only around 19% of the overall vote, and its center-left coalition around 23% in total.
Il Fatto Quotidiano had a front-page headline reading: "Everything will change".
Its leader, former prime minister Matteo Renzi, will speak publicly at 5 p.m. (1600 GMT), a spokesman said, with speculation swirling that he will resign.
The 81-year-old was forced to quit as prime minister in 2011 at the height of a sovereign-debt crisis and was widely written off following sex scandals, legal woes and ill health.
A topless Femen activist confronted Berlusconi on Sunday, jumping on a table as he was about to hand in his ballot and displayed "Berlusconi, you've expired" on her bare torso.
Former White House adviser Steve Bannon - the man who helped Trump ride a populist wave to power - characterised the election as "pure populism".
Italians voted Sunday in one of the country's most uncertain elections ever, marked by a far-right and populist surge, anti-immigration tub-thumping and a leading role for comeback king Silvio Berlusconi.
Bannon called a possible post-election deal between the Five Star Movement and the League "the ultimate dream".
Pollster Federico Benini, head of the Winpoll agency, said vote projections suggested that 5-Star and the League would be the largest two parties in parliament and would comfortably have enough seats to govern together if they wanted.
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