All aboard as country's electoral campaign gathers steam

Italys former prime minister Matteo Renzi chuffed off on a whistle-stop train tour of the country Tuesday as the nations main political contenders began campaigning in earnest for the upcoming general election.

Renzi, 42, who rode away on a centre-left Democratic Party (PD) train marked "Destination Italy", told journalists his aim was to "listen to and learn from" ordinary Italians as the left tries to fend off right-wing and populist gains.

But he may have to do more than catch a train to bump centre-right rival Silvio Berlusconi from the spotlight.

The ex-media mogul made a typically outrageous return to front-line politics this weekend, regaling supporters with a joke about Africans and oral sex.

Berlusconi, who had dropped out of the public eye following heart surgery last year, has said he wants the PM job.

With a nod to his friendship with the slain Libyan dictator Muammar Gaddafi, the 81-year old shrugged off his age, reviving and revelling in his reputation as the host of "bunga bunga" sex parties with young starlets.

The four-time former prime minister is banned from running for office due to a 2013 tax fraud conviction, but has appealed to the European Court of Human Rights to overturn it.

While a hearing is scheduled for November, a verdict is doubtful before the general election, which must be held by May at the latest. A date for the polls has yet to be set, but could come as early as March.

'Needle and thread'

If Berlusconi is unlikely to run, he will play a key role in rustling up votes for the centre-right, which is celebrating strong poll numbers and could seize power from the centre-left if it forms a coalition.

A poll on Monday taken by the Demos institute showed the anti-establishment 5-Star Movement (M5S) leading the pack with 27 percent of the vote, and the ruling centre-left PD snapping at its heels with 26 percent.

Berlusconi's Go Italy party and the anti-immigrant Northern League had around 14 to 15 percent of the vote each.

But should Go Italy and the Northern League band together with the small, nationalist Brothers of Italy party, together they would take home over 34 percent of the vote.

The parties would need to agree on a PM candidate that would appeal to voters from both the centre and far right.

The Northern League's head Matteo Salvini on Monday rubbished Berlusconi's suggestion a popular candidate could be chosen by polling, saying "this is not X-Factor" and insisting "I'll be prime minister by March".

The current electoral system means no party looks likely to win enough seats to govern alone -- a fact which may exclude the populist M5S from power as it refuses to join forces with traditional political parties.

Renzi's tour will take him first to towns in central Umbria devastated by earthquakes last year, before heading south.

Walter Veltroni, who served as the PD's first secretary when it was founded in 2007, warned the Florentine he would have to work hard to reunite a divided left which spends more energy on infighting than challenging the centre-right.

"I hope there is a needle and thread on the train to sow (the left) back together," he said.