South Carolina Rep. Joe Wilson released a fiery fundraising appeal late Thursday, calling himself a target of the left and vowing to push forward in his battle against President Obama’s health care reform effort.

“…I will not be muzzled. I will speak up loudly against this risky plan,” Wilson says in the video appeal on his campaign Web site.

Wilson’s combative video appeared 24 hours after he shouted “You lie!” at President Obama during a joint session of Congress after the president called the idea that his reform plan would provide insurance to illegal immigrants a myth. Wilson immediately faced a chorus of criticism, including from many in his own party...