The group issued a correction email once the error was realized:
(CORRECTION: We sent out this email earlier and made a glaring error that we apologize for. We mistakenly wrote Steve King when it is Peter King that we have issue with. Unlike Peter King, who has been attacking the Tea Party with lies and smears, we hold ourselves accountable for the inaccuracies we make. We are sorry to you and our friend Steve King for the mistake.)
The email was meant to attack the New York congressman for forming a new political action committee whose aim is to fight tea party favorites like Sens. Ted Cruz (R-TX) and Rand Paul (R-KY). King formed the PAC, the American Leadership PAC, to promote more establishment Republicans and counter conservative groups supporting Cruz, Paul and others.
"Unfortunately, Congressman King is out of touch with the majority of Americans who want to reduce the size, cost and intrusiveness of the federal government," the Tea Party Express email said. "If it were not for the Tea Party, Republicans would not be enjoying control of the House today."
(H/t: The Hill)