New tone:

Leave it to Robert F. Kennedy Jr. to one-up Rush Limbaugh in the name-calling department.

“Speaking of prostitutes, big oil’s top call girl Sen Inhofe wants to kill fuel economy backed by automakers, small biz, enviros, & consumers,” the New York-based environmentalist wrote Tuesday on Twitter.

Kennedy was targeting Inhofe for a letter the Oklahoma Republican sent last week to EPA Administrator Lisa Jackson that questions the Obama administration’s fuel economy and air pollution policies.

Politico, via Sweetness and Light.