Scott Brown is running as xenophobic a campaign as he can and lying like Richard Nixon seems to come very natural to him.

We can only hope that voters reject him for it.

Scott Brown, more frequently and with more aplomb than any candidate this year, has reacted to crises by telling potential voters how their government is failing them. It started in the summer, with the child migrant crisis, and it's continued with Brown warning that ISIS might cross the border, or that they might bring Ebola with them. In an interview with NH1,Brown rejected the idea that he was running on "fear"–Ebola, he said, was the "No. 1, 2, and 3" issue on the minds of voters he talked to.

"Carrying diseases doesn't need to be Ebola," said Brown. "but the whooping cough and polio and other types of potential diseases are coming through."

The quote hints at where Brown is getting with all this. It's 100 percent true that legal immigrants are screened for a host of diseases, and illegal border-crossers aren't. But the idea that illegal immigrants are responsible for the return of whooping cough was knocked downfour years ago, when incidence of the sickness ticked up in America. (The new cases probably had more to do with the anti-vaccine craze, more popular among affluent whites than among Latinos.) Polio hasn't been seen in this hemisphere in decades–the threat is so remote that the Americas don't even appear on the Global Polio Eradication Initiative's map of known cases.

Are there diseases south of the border that the U.S. government wants to keep out? Obviously, absolutely, and the voter who pays fitful attention to the news may have heard of the "polio-like" disease, Enterovirus-D68, that re-emerged this year. The fear of polio or whooping cough crossing the border, though -- that, typically, has come from immigration restriction activists. Brown's claim is that whooping cough and polio are straight-up "coming through" the border right now. It's a "rational fear," if you ignore the many rational reasons not to panic about it.