Is Campbell a threat to DeLay? I find it hard to believe Mr. Campbell is going to win a primary against DeLay. But he doesn't have to win to do damage to DeLay. DeLay needs to win with a substantial number of votes, so he can demonstrate that he is the standard-bearer for his party.
He is fighting against something that is very hard to fight against, which is the tide of public opinion. It is possible, come December, he could be in a tight race.