I've seen a number of people saying the same thing, but finding anything concrete is tough. I've also seen people (who mostly seem to be connected to Venezuela in some way) claiming that nobody cares. I can understand the frustration, but it's not something that the public has had much access to. The bolivar has also been devalued and that seems to have coincided as public sentiment was already approaching critical mass, but that's just a guess.
So I've been reading and I guess the question is to what extent is the US involved. It being Venezuela, I imagine we should start our guess at 100 percent and work our way down. EDIT: and I'm not at all clear exactly what Lopez would do if he were actually put in charge of the country. He barely seems to have a political platform.
I don't think there's any evidence that the US is involved, which of course means nothing, especially if any involvement is done "well". It's hard to say though, since Chavez was pretty heavy on the anti-American imperialism rhetoric and I think Maduro is too. I won't say that I'd be surprised at some involvement, but consider that Maduro only won by a 1.5% margin (so I've read) and generally seems to have been at a disadvantage from the get-go. Following Chavez has got to be tough. As for Lopez, I'm interested to know myself. From the brief articles I've read, it mostly seems that he's running on a platform of "I'm not Maduro" which might be enough. Anyway, allying himself with the student protesters is a smart move regardless of his platform. Hopefully he actually does have the people's interest at heart.