There is no 3rd party candidate because there is no 3rd party of any significance. And there will be none as long as the route to pursuing such a thing is being done through elections. This, as attempted by Ralph Nader, as a progressive, H. Ross Perot as a right-libertarian and other, lesser known names, is a flawed scheme because it puts the cart before the horse. You don't build a party by running for president. You build a party by organizing from the bottom up. It begins with local elections (and there are municipalities across the USA that have 3rd party representatives), but it has to build gradually. The support has to be gathered on a local, then city, then state and only then federal, basis. Then there can be a viable base of both people and, yes sorry to say it's necessary, money to contend with the business parties. Doing it the other way around ignores the people. Because sure, a leftist will vote for Ralph Nader, or Bernie Sanders, or any number of other smart and dedicated people who could do the job. But that won't help. Before a 3rd party presidential candidate can mean something, the left needs to convince working people that they need to stop supporting Democrats and Republicans and chart a whole new course. We've done an awful job of that, in part because it's hard, it involves pissing off a lot of people who should be allies and it is an effort that is not going to show immediate results. So instead, every once in a while we vote for a Nader and nothing comes of it. Even if Bush is the result, and things turn disastrous, we do not gain from that. Indeed, the radical outcome of the Bush years was only marginally on the left--it was much more impactful on the right, with the growth of right-libertarianism and, most obviously, the Tea Party. Sure, these movements found super-rich funders like the Koch Brothers, but they were begun with the rage of working class people. And the greater part of that rage didn't flow to the left, it flowed rightward. We can blame all sorts of factors for that, including the news outlets, and other factors. And that may not be incorrect, but it's not helpful. There's more than enough that we can do to more effectively send out our own message. Until that base is built, running a Nader in the race does nothing but ensure a right wing victory, one which will not, as has been demonstrated, make things so bad that people will run to the left. There are reasons why the USA works that way; because rightward extremism does in fact turn people toward the left in much of Europe (and vice versa), at least more so than in the US. That's due to history and the role ideology plays in the different cultures, etc. But it's also due to a lack of strategic vision and, often, effort on the part of the American left. We spend a lot more energy bemoaning the deck stacked against us than we do mobilizing for change. It's far more helpful to ourselves if we accept the stacked deck and instead focus on how to achieve our aims strategically. It starts with unity on the left, that very elusive beast. It continues with improving our communications and working to gather funds, two things most leftists I know hate doing. Because the left has the strength of being just and egalitarian, two things the right cannot be, by definition, so we do not need billions of dollars and massive marketing efforts to convince people of the rightness of our view. But we do need to put a lot more effort in, and we need some level of skilled mass communications and funds. We don't do these things. Instead we think about presidential elections, which are self-defeating efforts for those of us outside the system--they are the last step, not the first.