Rick Perry must be afraid that if the people of Texas see him live in a debate with his opponents, he will lose votes - perhaps enough to cost him the election. Why else would he be only agreeing to a single debate, and making sure that debate happens at a time when the fewest number of Texans would be watching. These are the actions of a candidate sitting on a small lead, and terrified that his opponents will further chip away at that lead.
Perry has agreed to meet his opponents in a debate in Dallas next friday night. According to his campaign, it was the only date and time that he had open. If you believe that, I'd like to talk to you about some ocean-front property for sale here in Fort Worth. This date and time just happen to coincide with friday night football all over Texas, where district play is just getting underway. If you know anything about Texas, and its unofficial religion of football, then you know that a significant portion of Texas' population will be watching high school football - not a political debate.
Making matters even worse is the fact that next weekend is Texas-OU football weekend. There will be thousands of people in Dallas, but they will be wearing burnt orange or crimson and partying their butts off - again, not watching a political debate. If Perry wanted to make sure that the fewest number of people possible would be watching the debate, then he picked the perfect time.
In the latest polls, Perry only has 30%-33% of the vote. This may be just enough to put him over the top. A real debate, with Texans actually watching could cost him the election. He knows that. That's why the debate was scheduled for next friday night.