I'd take this perspective on Melenchon with a grain of salt.

It is written by a Macron backer, the former Le Monde editor. Melenchon has been around for decades, and it is a bit surprising to see him break through so suddenly and so late in his career. But he is riding the wave of Corbyn-Sanders socialist chic that the kids are lapping up these days. Nougayrède warps a bit Melenchon's actual platform and his words in this piece, imho. His anti-german rhetoric is a pretty standard and correct critique of ECB monetary policy, effectively run by the Bundesbank, that favors the German economy over that of France and southern Europe. His economic policies look like a package of mainstream Piketty-endorsed initiatives and reforms. The comments about 'annexation' of East Germany have more to do with the East Germans discontent with the destruction of their social safety net aftet 1990 than dark intimations of a new Nazi revival. Sure, he doesn't see globalisation with the doe-eyed affection that Macron does, but it does not make him an Ersatz Le Pen. Feels like a smear piece to me. 

Could a Leftist Bring Growth Back to France?

Op-Ed by Mark Weisbrot @ NYTimes.com, April 20

Some dismiss Jean-Luc Mélenchon as a far-left populist. That’s a mistake.

About Weisbrot from Wikipedia:

Mark Weisbrot is an American economist, columnist and co-director, with Dean Baker, of the Center for Economic and Policy Research (CEPR) in Washington, D.C. His writing has appeared in publications such as The New York Times, The Washington Post, Los Angeles Times, The Guardian, and Brazil's largest newspaper, Folha de S.Paulo. He is a regular columnist at The Hill (newspaper) and with Tribune Content Agency.[1] Weisbrot is also president of Just Foreign Policy, a non-governmental organization dedicated to reforming United States foreign policy.[2]

As an economist, Weisbrot has opposed privatization of the United States Social Security system and has been critical of neoliberal globalization and the International Monetary Fund (IMF). He has supported efforts by South American governments to create a Bank of the South, in order to make them more independent of the IMF. Weisbrot's work on Latin American countries (including Argentina, Bolivia, Brazil, Ecuador and Venezuela) has attracted national and international attention, and in 2008 was cited by Brazilian Foreign Secretary Celso Amorim.[3] His work on Greece’s ongoing debt crisis has influenced the debate[4] over what measures the Greek government should take in negotiating a solution with the European Central Bank, European Commission, and the IMF, including with Greece’s former Finance Minister Yanis Varoufakis[5] and current Prime Minister Alexis Tsipras.[6]