John McCain made a quick stop at the Capitol one day last spring to sit in on Senate negotiations on the big immigration bill, and John Cornyn was not pleased.

Cornyn, a mild-mannered Texas Republican, saw a loophole in the bill that he thought would allow felons to pursue a path to citizenship.

McCain called Cornyn's claim "chicken-s---," according to people familiar with the meeting, and charged that the Texan was looking for an excuse to scuttle the bill. Cornyn grimly told McCain he had a lot of nerve to suddenly show up and inject himself into the sensitive negotiations.

"F--- you," McCain told Cornyn, in front of about 40 witnesses.