CNN announced today that it's hosting a presidential debate with the discredited Tea Party Express next summer.

In July, the Tea Party Express was expelled from the National Tea Party Federation for a racially charged post on then-spokesman Mark Williams' blog. Williams had penned a fake letter from the NAACP calling Abraham Lincoln the “greatest racist ever” for taking away the “great gig” of slavery from African-Americans. The Tea Party Express still doesn't appear on the membership list of the National Tea Party Federation.

Even afterward, CNN was still inviting Williams on the air and dispatching a producer to a Tea Party Express tour.

While Fox News has heavily promoted the Tea Party Express -- a group that was launched by GOP consultants -- other Tea Party groups have denounced it as little more than an extension of the Republican Party.

As the New York Times reported, Phillip Glass of the conservative group National Precinct Alliance called the Tea Party Express a “Republican National Committee-related” group. Dave Weigel reported in October 2009 that other Tea Party activists view the Tea Party Express as “a scheme for Republican strategists and candidates to take advantage of a movement that was chugging along fine without them.”

What will it take for CNN to hop off the bus?