As Pedro Sanchez navigates through rough seas while attempting to form a government, he should take, from time to time, a quick look at the travelog of his Greek socialist comrades' unfortunate expedition of a few years ago. PASOK (Greek Socialist party) and PSOE (Spanish Social party) share an astonishingly similar, almost identical history. They both started after democracy was restored as radical parties and managed to secure hegemony on the left, out-winning a strong communist political tradition. They became main opposition parties at the same time, in 1977, and triumphantly rose to power with exactly the same score, 48 percent of the vote, practically at the same time -- 1981 for Papandreou, 1982 for Gonzales. They ruled their countries for 20 out of the next 30 years, both lost power in 2011 and they were both unlucky enough to be in power during the cataclysm of the economic crisis. What happened next? In Greece, Papandreou's government first lost its nerve, confronted by widespread social malaise, and then lost its parliamentary majority in November 2011, after agreeing on a second bail out. PASOK went on to form a six-month transitory government in an unhappy alliance with its arch-rivals, the conservatives of New Democracy. When Greeks returned to the polls, in May 2012, we found out that one of the most powerful and stable two-party political systems in Europe, had collapsed. The two parties that shared 78 percent of the vote in October 2009, managed to secure just 32 percent -- 19 percent for ND and 13 percent for PASOK. PASOK finished third, behind SYRIZA, which vaulted from 4.6 percent in 2009 to 16.8 percent in 2012. It was one of the greatest electoral disasters ever to be recorded. It was made worse by mishandling the electoral results. PASOK could not, or would not, get SYRIZA to agree on a new parliamentary majority. The inevitable new elections in June helped N.D. secure first place but SYRIZA was the most favored party. Its lead over PASOK went from 3.8 percent in May to 15 percent in June. Game over! PASOK shared power with New Democracy for another 30 months, as a junior and almost invisible partner in a government that was implementing a highly unpopular austerity policy under the humiliating guidance of the Troika. When election time arrived again, in January 2015, PASOK had totally lost contact with its traditional electoral audiences. What had been for over 30 years the "natural party in government" scored a modest 4.7 percent of the vote. No one expects them to bounce back to glory. SO WHAT IS TO BE LEARNED FROM THIS MODERN GREEK TRAGEDY? * That it is very risky, in times of crisis, when there is no way for politics to be popular while in power, to give a radical, populist (in the good and in the bad sense of the term) political formation the luxury of irresponsible opposition. N.D. and PASOK thought that by treating SYRIZA as outcasts, negating due respect to a new political player, refusing even to meet Alexis Tsipras, they would de-legitimize him. On the contrary, they helped him secure an electoral win and postponed what SYRIZA's second in command, Dragasakis, called "the process of political maturity" after six disastrous months in power. * That a two-party political system, like the one Greece and Spain had in common for over 40 years, cannot survive the, at times maybe inevitable and at other times even gallant, experience of a partnership in government of the contesting parties. * That the socialists have to reinvent themselves in order to survive. They were successful, under Mitterrand, Gonzalez or Papandreou in the '80s in inventing a new political brand that inspired electorates. They bounced back in the coming decades, under Simitis and Papandreou Jr. in Greece, Zapatero in Spain, as a new, liberal, reformist centre-left guarantor of the social state in times of liberal globalization. The question is: Can they do it again? Or are they going to be taken over by those new political formations that are using their own old trick -- a radical stance when in opposition that turns realist when in power. _This post first appeared on HuffPost Spain. It has been translated into English and edited for clarity._ -- This feed and its contents are the property of The Huffington Post, and use is subject to our terms. It may be used for personal consumption, but may not be distributed on a website.