The long fundraising email repeatedly refers to the senior Republican senator, rated the second-most conservative in the Senate, as "liberal John Cornyn," and criticizes him for opposing Sen. Ted Cruz's (R-TX) effort to only fund the federal government if Obamacare is defunded.
"Liberal John Cornyn claims to oppose Obamacare, but he votes to kill any effort to stop it because he agrees with the D.C. establishment and thinks it will buy him votes," Stockman writes in the email.
Stockman goes on to write that "John Cornyn wakes up every morning and works to make the Senate a more liberal place."
Stockman's criticism is the same sort of attack conservative challengers have made against their opponents in Republican primaries this cycle, even when, as with Cornyn, the target is rated as one of the more conservative lawmakers in Congress.
Read the full email here.