ROME (Reuters) - Three days after resigning as Italian prime minister and before his successor took office, Matteo Renzi typed a late-night Facebook post from his family home near Florence that seemed to cast doubt on his future.

FILE PHOTO: Italian Prime Minister Matteo Renzi speaks during the last rally for a "Yes" vote in the referendum about constitutional reform, in Florence, Italy, December 2, 2016. REUTERS/Alessandro Bianchi/File Photo

“I have no seat in parliament, no salary, no pension... I’m starting over,” he wrote.

Since stepping down on Dec. 7 after a crushing referendum defeat over his flagship constitutional reform, newspapers have conjured up images of Renzi sitting in rush-hour traffic while driving his three kids to school, writing his memoirs and entertaining lucrative job offers outside politics.

But the truth is that Renzi has set up an office in his basement where he meets advisers and spends hours on the phone with party allies plotting his path back to power, two sources close to the 41-year-old said.

Renzi staked his government on the plan designed to make Italy more governable but which almost 20 million voters rejected in the referendum. The loss left him, and his Democratic Party (PD), “navigating without a compass”, one PD source said.

The former boy scout’s rise from the political ashes is far from certain. But he appears determined to capitalize on his continued appeal within the PD and looks keen to shape Italy’s future political landscape.

Renzi, who remains leader of the party, fears his absence could open the door to extremists on the right and left.

Any comeback would probably involve championing progressive reforms while challenging European budget austerity and migrant policy, as he did during his first - and so far only - term that lasted less than three years.

Despite the disagreements with Brussels, he wants to keep Italy at the heart of the European project, unlike the increasingly popular anti-euro 5-Star Movement which would be one of the main obstacles to a return to office.

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Even if he does succeed, it may mean teaming up with former premier Silvio Berlusconi - as the PD had to do in 2013 - to keep the 5-Star out of power.

No clear winner would emerge if an election were held now, according to opinion polls, with the PD, the centre-right and anti-establishment 5-Star each drawing a third of voters.

First, Renzi will have to reassert his hold on the fractious PD. But if that fails, he is ready to consider forming a new party, provided a new electoral law makes that advantageous, two separate PD sources told Reuters.

Unlike in Britain, where David Cameron left politics soon after losing the Brexit referendum, Italy has a history of prime ministers returning to power after defeat. Berlusconi had four terms while Christian Democrat Giulio Andreotti served five times as premier from the 1970s to the 1990s.

On Sunday, Renzi stood before more than 1,000 PD members and pledged “an extraordinary listening campaign” to electors in January as the party enters a “Zen” phase of reflection before moving forward.

Silence and meditation have never been traits associated with the fast-talker, who was Italy’s youngest prime minister when he seized power in a party coup in 2014. Three months later, the PD won almost 41 percent of the vote in European elections, a level of consensus last reached by the then-dominant but now defunct Christian Democrat party in 1958.

RENZI’S POPULARITY

Renzi’s return to Tuscany and a rumored new book belie a tactical threat to PD rivals who want him to step down as party secretary and make way for new blood, PD sources said, because his retreat would leave the party severely hobbled.

The PD would win only about 10 percent of the vote if Renzi left the party and ran solo, two separate polls showed. Even after the referendum, his leadership was backed by between half and two-thirds of PD voters, two different surveys showed.

“I’m convinced that - as polls say - Renzi is the leader recognized by the PD base by a huge margin compared with other candidates,” Anna Ascani, a PD lawmaker close to Renzi, told Reuters.

Roberto Speranza, a member of the minority left-wing faction of the bloc, has already said he would run for the party leadership, and two others have expressed a similar aim, but none of them has nearly the same following as Renzi.

“It’s in Renzi’s interest to accelerate the process and go to a vote as soon as possible to head off any internal rivals,” said Federico Benini, the head of polling agency Winpoll.

It is still unclear whether there will be early national elections in the first half of 2017, or whether the legislature will head to the end of its term in 2018. Renzi has said he favors a snap vote.

But parliament is unlikely to adopt new voting rules until after a Constitutional Court ruling on the lower house electoral law, which is expected at the end of January. The court will also rule on whether to allow another referendum - this time on Renzi’s labor reform - in January.

Meanwhile, Renzi is in his basement putting into practice the boy scout motto he knows well - “Be prepared”. In 2009 his election as Florence’s mayor proved to be a springboard to the prime ministership. Before getting there, however, he lost a 2012 primary election to party rival Pier Luigi Bersani.

“A leader is someone who admits a loss and then says, ‘Let’s see how we can restart again,’” Renzi said on Sunday as most of the party members in the auditorium cheered him on.