I would be surprised if french soldiers fighting Russia in Ukraine would be a vote winner for him...
Historically, French soldiers fighting in Russia, had an extremely damaging effect on French leaders' popularity. Haha.
In fact, in both of the instances during the 19th century when France attacked Russia - it eventually led to a collapse of France. Put that in your pipe, Mr. Macron!
Napoleon's defeat in Russia, effectively ended the French Empire.
Napoleon III's ill advised entrance into the Crimean War, together with the British, nearly bankrupted France, led to the death of 100,000+ Frenchmen, destroyed the balance of power in Europe, and ultimately led to France being destroyed by Prussia (Prussia attacked only after it carefully arranged Russian non-intervention, which it secured by promising Russia support in abrogating the Treaty of Paris).
That for France to fight in Russia is a bad idea, seems like a point that hardly requires explanation. It would be comical, if it wasn't so sad.