First, we had George W. Bush (the GOP Presidential nominee in 2000 and 2004) who was a mediocre student at Yale in the era before admissions we are merit based as they are today (although his father, George H.W. Bush, was a quite intelligent man with real academic talent and senior civil service experience as C.I.A. director), who went on from the Texas Governorship to become President.
Arizona Senator and 2008 GOP Presidential nominee John McCain was also a mediocre college student at the U.S. Naval Academy:
McCain came into conflict with higher-ranking personnel, and he did not always obey the rules, which contributed to a low class rank (894 of 899), despite a high IQ. He did well in academic subjects that interested him, such as literature and history, but studied only enough to pass subjects he struggled with, such as mathematics.
Sarah Palin, McCain's Vice Presidential nominee was also a pretty mediocre college student and known for her lack of a command of policy issues on the campaign trail as well.
Now, Rick Perry, a 2012 Presidential candidate with the same political credentials as George W. Bush, however, makes George W. Bush look like a genius by comparison to any of these other candidates, given is truly dismal performance at Texas A&M.
…In his freshman and sophomore year, Perry struggled with core science classes, earning D’s in several organic chemistry classes and C’s in general chemistry and physics.
But after Perry switched his major at the beginning of his fall semester in 1970, his grades didn’t improve. Perry got a C in Reproduction in Farm Animals, a C in genetics, a D in Feeds & Feeding, a C in Sheep & Angora Goat Production and two C’s in animal breeding classes.
Many of Perry’s other classes involved military education. Perry has previously credited his time in the A&M Corps of Cadets with giving him the necessary discipline to complete school.
Perry got two C’s in Development of Air Power and took four levels of World Military Systems, earning two C’s, a B and an A. The A was one of only two Perry earned at college — the other was for a class called Improv. of Learning.
The future governor only took one political science class while he was in school — American National Government, for which he earned a B. Other classes outside of Perry’s major included Shakespeare and Writing for Professional Men, which earned him two D’s.
Perry took two summer sessions before his senior year but still needed two more after the rest of his class graduated to complete a degree. He graduated in August of 1972.
Like George W. Bush, Rick Perry was a cheerleader in college.
While college grades are not the be all and end all of life, I'd think we could expect a bit more of people who want to rule the free world.