On 15 October 2015, the website DailyLeak published an item claiming that Vladimir Putin endorsed Democratic candidate Bernie Sanders for President. In March 2016, that post began circulating again on social media, claiming:
“The clear winner [of a then-current debate] was Sanders. Clinton side-stepped the real issues while Sanders showed his willingness to embrace change. He would be the best choice from all candidates running,” the Russian President stated.
“We support the socialist government of America,” Putin said. Continuing, “Any 4th grade history student knows Capitalism has failed in every country, at every time in history. President Obama and his democrats are either idiots or purposely trying to destroy they own economy. And it’s my deep belief that any actions to the contrary in order to destroy the government will create a lawless situation which you can witness now in the other countries in the West.”
Putin stated that Sanders must win to reduce gun violence in America and achieve lasting peace between their two countries.
In December 2015, BuzzFeed (a non-satirical site) posited that Putin endorsed Trump, but whether Putin's commentary constituted an endorsement was subject to interpretation.
As for the October 2015 DailyLeak item, there was no truth to the claim. On the site's "About" page, its content is clearly marked as "for entertainment purposes only":
All information, data, and material contained, presented, or provided on DailyLeak.org is for entertainment purposes only ... The Daily Leak is a satirical, parody website.
The Daily Leak uses invented names in all its stories, except in cases where public figures are being satirized. Any other use of real names is accidental and coincidental.