On October 18, Hillary Clinton said in a podcast that the Russians are grooming someone to be a third party presidential candidate, and she also said that Jill Stein (Green Party presidential nominee in 2012 and 2016) was a tool of the Russians. See this story.
Tulsi Gabbard, whom Clinton did not name, has already said that she will not be a presidential candidate in the general election (unless she gets the Democratic nomination, of course, which is considered impossible).