Robertson was suspended from his A&E reality television show for making anti-gay comments during an interview with GQ magazine, but he will return to the show for the fifth season.
King got himself into hot water in July when he said young undocumented immigrants have "calves the size of cantaloupes because they're hauling 75 pounds of marijuana across the desert."
King wrote in the fundraising email that he has been a "top target of the left," along with former Rep. Allen West (R-FL) and Rep. Michele Bachmann (R-MN), but that he will not back down in the face of criticism.
"Tolerance has never been a two-way street with the left. Time and time again conservatives are lambasted for stating their opinions, the opinions derived from faith, family, and an understanding of history. Once again the left encourages a double standard to advance their agenda," he wrote. "As you know, I have not and will not back down. And like other conservatives who stand their ground, I’m always a top target of the left."