Front-page, must-read extensive NYT article on “True the Vote.”  It begins:

It might as well be Harry Potter’s invisible Knight Bus, because no one can prove it exists.

The bus has been repeatedly cited by True the Vote, a national group focused on voter fraud. Catherine Engelbrecht, the group’s leader, told a gathering in July about buses carrying dozens of voters showing up at polling places during the recent Wisconsin recall election.

“Magically, all of them needed to register and vote at the same time,” Ms. Engelbrecht said. “Do you think maybe they registered falsely under false pretenses? Probably so.”

Weeks later, another True the Vote representative told a meeting of conservative women about a bus seen at a San Diego polling place in 2010 offloading people “who did not appear to be from this country.”

Officials in both San Diego and Wisconsin said they had no evidence that the buses were real. “It’s so stealthy that no one is ever able to get a picture and no one is able to get a license plate,” said Reid Magney, a spokesman for the Wisconsin agency that oversees elections. In some versions the bus is from an Indian reservation; in others it is full of voters from Chicago or Detroit. “Pick your minority group,” he said.

The buses are part of the election fraud gospel according to True the Vote, which is mobilizing a small army of volunteers to combat what it sees as a force out to subvert elections. Ms. Engelbrecht’s July speech in Montana was titled “Voter Fraud: The Plot to Undermine American Democracy.”