Republican presidential candidate Ted Cruz asked his campaign spokesman to resign for tweeting a story that falsely alleged Marco Rubio insulted the Bible.
Cruz told reporters he asked for Rick Tyler's resignation.
Rubio had blasted Cruz for the incident and asked whether Cruz would fire anyone involved.
Cruz said Tyler was "a good man" and deleted the tweet once he found it was false.
"We are not a campaign that is going to question the faith of another candidate for president," Cruz told reporters.
Tyler had earlier apologized for his role in promoting the falsehood.
It was the second time the Cruz campaign or the candidate himself has apologized for campaign conduct. Cruz apologized to rival Ben Carson earlier in the month after his campaign incorrectly cast a news story as evidence that Carson was getting out of the race.
Rubio had accepted the Cruz campaign's apology, but added: "At some point there has to be some level of accountability. Otherwise...you're sending the message to the people who work for you: Go out and do anything you want and if you get caught we'll just apologize, but we'll keep doing it."
Republican frontrunner Donald Trump wasted no time in responding to the latest development.
"Wow, Ted Cruz falsely suggested Marco Rubio mocked the Bible and was just forced to fire his Communications Director," He wrote. "More dirty tricks!"