Why do the media and pollsters give Nader preferential treatment over other third party candidates?

Who is the most popular third party/independent candidate running for president? If we're to believe this graph, it's not Nader -- he doesn't even come in second.

These are the latest statistics from Ballot Access, a website which keeps track of how many state ballots non-major party candidates will appear on. It clearly shows the Libertarian's Badnarik with a commanding lead, Constitution Party's Peroutka coming in second. Nader is at third with only the potential to overtake Peroutka, but he's still eating Badnarik's dust.

So if more Americans will have to opportunity to vote for Badnarik and Peroutka, why is it that not one polling agency bothers to name them as a candidate when they ask potential voters who they'll be casting their ballot for? If Badnarik and Peroutka are on more state ballots than Nader, then there's no questioning the fact that they've had more grassroots support, and thus, they are more popular than Nader. Let's not forget that the Republicans contributions of money and volunteers to Nader have been invaluable in his effort to get on as many state ballots as possible, along with all the media atention he has received since January. No other third party candidate has had this backing, and yet, Nader still hasn't reached the levels of popularity obtained by Badnarik and Peroutka. Hell, his popularity even against Green's Cobb is questionable, since it was Cobb who beat out Nader for the nomination at the Green Party convention.

Yet whenever we see a poll telling us who Americans will vote for, Nader is the only other candidate listed if it goes beyond Bush and Kerry. Why don't pollsters ask potential voters, "Who do you intend to vote for: Kerry, Bush, Badnarik, Peroutka, Nader, or Cobb?"

You probably already know that members of the Libertarian and Constitution Parties lean to the right, and if they weren't in the race, some of their voters would instead cast their ballots for Bush. So third party candidates who could spoil the election for Bush are being ignored by the media and the pollsters while they have no problem with giving all their attention to the candidate who's most able to take votes away from Kerry.

Why are Badnarik and Peroutka blacked out of the media and polls when they have more support than Nader? Isn't that a bit biased?

[Crossposted to Rox Populi.]