GOP worried about Gary Johnson playing spoiler?

The fear of Mr. Johnson’s tipping the outcome in an important state may explain why an aide to Mr. Romney ran what was effectively a surveillance operation into Mr. Johnson’s efforts over the summer to qualify for the ballot at the Iowa State Fair, providing witnesses to testify in a lawsuit to block him that ultimately fizzled.

Libertarians suspect it is why Republican state officials in Michigan blocked Mr. Johnson from the ballot after he filed proper paperwork three minutes after his filing deadline.

And it is why Republicans in Pennsylvania hired a private detective to investigate his ballot drive in Philadelphia, appearing at the homes of paid canvassers and, in some cases, flashing an F.B.I. badge — he was a retired agent — while asking to review the petitions they gathered at $1 a signature, according to testimony in the case and interviews…

Mr. Johnson said he had no problem being labeled a potential spoiler in an election that he views as “a debate between Coke and Pepsi.” (He said he viewed himself as Perrier.)