The walls continue to close in on Lance Armstrong as he's just been dropped by his biggest sponsor on the same day that he's quitting as the head of the charitable foundation that he built. A statement released by sports apparel giant Nike makes it clear that their decision to end his contract was not a mutual separation, saying they were "misled" by Armstrong and explicitly blames his apparent use of doping and other performance enhancing drugs during his cycling career.

“Due to the seemingly insurmountable evidence that Lance Armstrong participated in doping and misled Nike for more than a decade, it is with great sadness that we have terminated our contract with him. Nike does not condone the use of illegal performance enhancing drugs in any manner. Nike plans to continue support of the Livestrong initiatives created to unite, inspire and empower people affected by cancer.”

Speaking of Livestrong, at the same time Nike announced the firing, Armstrong himself announced that he will step down as the chairman of the cancer-fighting charity. He will remain on the board of directors, but says that he wants "to spare the foundation any negative effects as a result of controversy."

The loss of Nike and Livestrong means the loss of what may be Armstrong's final two outlets of support amid all the doping allegations. As long as he had his biggest sponsor, he could weather the storm of bad publicity and the loss of his actual cycling career. (He's currently under a ban from international cycling events.) And the charity work that Livestrong and its ubiquitous yellow bracelets have fostered are the one thing that Armstrong's remaining fans have clung to as evidence of his good nature. Yes, he may have cheated to win seven Tour de France races, but don't forget all the good that he's done and the inspiration he's provided to cancer survivors. Livestrong and Nike will go on without him, but it now appears that Armstrong himself has no other options than to quietly fade into the background and live with his disgraced reputation.

Update: One other reason why Nike chose to dump Armstrong now is that accusations were beginning to fly that the company was complicit in covering up failed drug tests and helped him with his cheating. It's one thing for a client to be accused of wrongdoing (as Armstrong has been for years), but when that starts to blow back on the company they have to put a stop to it.