Unsuccessful in the first round of voting, France's socialist presidential candidate, Jean-Luc Melenchon (pictured), stopped short of endorsing the centrist Emmanuel Macron, though he warned his followers not to turn to the right-winger, Marine Le Pen. A vote for her party, the National Front, would be a "terrible mistake," he told French broadcaster TF1.

The political situation in France is not unique. In many countries, the right wing is on the rise while the entire left side of the political spectrum - from socialists to social democrats - languishes in existential crisis. The US election is but one example, with Democrats too preoccupied with internal matters that they underestimated the danger of a Trump victory over Hillary Clinton.

Jeremy Corbyn and his Labour Party in the UK were too weak to confront the Brexit campaign's Leave camp. Labour is trailing in polls ahead of early elections scheduled for June 8. Citing both UK's Labour and US Democrats as examples, Peter Grottian, a political science professor at Berlin's Free University, sees weak opposition and internal struggle as a boon for right-wing populists.

Out of touch

"The left has a problem," wrote Simone Rosa Miller in "Die Zeit," a German weekly. "Since Donald Trump's victory in the US, there has been a diagnosis for its failure and own contribution to the rise of the new right in the West." By associating itself too closely with issues important to social minorities, the left lost touch with wider society, she added.

Left's slogans, right's conviction

In many countries, the right has co-opted many left-wing issues. Populists like Le Pen, Trump and Germany's Alternative for Germany party (AfD) are using the old left's anti-establishment playbook from the '68 Movement.

In France, both the National Front and the socialists share a common cause to "dethrone the powerful," Grottian said. "Many voters in France are ready to swing from the left to the right because they want to kick the ruling class in the knees." A similar readiness to change sides is present in Germany, he added, reason enough for left-wing politicians like Sahra Wagenknecht to worry.

While the left in France has dwindled in the political scene, the threat posed by Le Pen has grown with her ability to combine left- and right-wing criticisms of European and German economics. Either way, "she appears anti-establishment."

Across Europe, left disappoints

In Spain, Ireland, Poland, the Netherlands and Greece, the left has its back to the wall. Ireland's Labour Party dropped from 19.4 percent to 6.6 percent in 2016 general elections. Spain's social democrats have been in the uncomfortable position of supporting a conservative minority government since October 2016. Poland's left didn't survive general elections in October 2015. In Greece, the austerity measures Prime Minister Alexis Tsipras has had to agree to have left his leftist party, Syriza, trailing in opinion polls.

A glimmer of hope

The downfall of socialist and social democratic parties does not automatically spell victory for the far right. In Dutch elections earlier this year, the social democrats suffered a major defeat, however the pro-EU Greens took 14 percent of the vote. The liberal party remained firmly ahead of far-right populist, Geert Wilders, giving Mark Rutte another term as prime minister.

"The demystification of far-right populists has already begun," Grottian said. The AfD's best days are behind it because refugees are no longer a leading campaign issue. "People are more afraid of Trump than some refugee," he added.