Pierluigi Bersani, 61, is a former communist of working-class origins who in Sunday’s primary election relied on his loyal trade union base to defeat Matteo Renzi, the mayor of Florence and upstart 37-year-old challenger.

With opinion polls estimating the Democratic party’s national support at 30 per cent, far ahead of its rivals, it seems that Mr Bersani is well-placed to become prime minister of a left-leaning coalition government after parliamentary elections expected in March.

Both in Italy and across the Mediterranean, however, the outlook for the traditional parties is more mixed than Mr Bersani’s success implies. The most suggestive development in Italian politics remains the decomposition of the centre-right forces that have dominated the national stage since 1994. Former prime minister Silvio Berlusconi’s People of Liberty party, once known as Forza Italia, is in headlong retreat. Much of its support is leaking to the idiosyncratic, “a plague on both your houses” Five-Star Movement of comedian Beppe Grillo.

But the appeal of political iconoclasm has its limits, even in a country whose party elites are as discredited as in Italy for bringing their country to the edge of financial disaster. Immediately after the second world war, an anti-establishment party known as Uomo Qualunque (Common Man) stormed on to the scene, winning well over 1m votes in the 1946 and 1948 elections and gaining a couple of dozen seats in parliament.

Staying power?

Yet qualunquismo vanished almost as fast as it appeared, swamped by Christian Democrats on the right and communists on the left. The question is whether Mr Grillo’s movement will outlast the inevitable revival of Italy’s centre-right after Mr Berlusconi finally bows out.

Greece offers the clearest example of the collapse of the established order. Until the 2009 debt crisis, politics had been controlled since the end of military rule in 1974 by two parties: conservative New Democracy and socialist Pasok. But in a general election six months ago, the combined vote of these two parties was barely 42 per cent.

Pasok, in particular, with a mere 12.3 per cent, looked like a spent force. Voters flocked instead to Syriza, a more explicitly leftwing alternative. But apart from the obvious fact that the electorate was voicing its rage at Greece’s descent into the abyss, one reason why the mainstream parties haemorrhaged support was that they had much less patronage to offer in exchange for votes.

The party systems constructed inSpain and Portugal after the democratic transitions of the 1970s are, for the moment, holding up better than in Greece. At national level – though not at regional level in Spain – the contest is largely between one big party on the right and one on the left. Change is blocked by the highly centralised nature of these parties and by the power of party leaderships to hand-pick candidates at election time, with no input from ordinary party members or voters.

Rajoy support in free fall

Yet there are shades of difference between Spain and Portugal. Whilst the popularity ratings of Mariano Rajoy, the centre-right prime minister, are in free fall, Spanish citizens evince no more liking for Alfredo Pérez Rubalcaba, leader of the Socialist opposition. Even among his own party’s voters, there is a striking absence of faith that Mr Rubalcaba would govern Spain more effectively than Mr Rajoy.

If Spain displays some conditions essential for a reshaping of the party system, this appears less true for Portugal.

There, the ruling centre-right Social Democrats and opposition Socialists retain their ability to frame the attitudes of a people who often seem more politically passive than their Spanish cousins. In 1975, when Portugal held its first free election in five decades, turnout was 92 per cent. But in last year’s national election it was 58 per cent.

It is a sobering thought that, even in an age of crisis, young people born into a democratic society vote less than their parents, who experienced authoritarianism first-hand.