Rick Perry is the longest serving governor in the history of the state of Texas and has launched a campaign based around strong statements on states rights and getting Washington off the backs of the people. His statements are somewhat in contrast to his long record as a government insider and supporter of federal programs. He is perhaps best known in Texas for his friendliness to large corporations and the inside deals and special favors which have been hallmarks of his administration. This is Perry's first debate and there is some speculation that he is not well prepared and may suffer based on his history of being a weak debate performer, or may even duck out at the last minute citing the wildfire crisis in Texas as a reason not to attend.
Ron Paul is probably the highest profile candidate. He is a 10 term Congressman from Texas known by his colleagues as "Dr. No" for his consistent opposition to any growth of government spending or programs and any legislation of questionable constitutionality. Paul ran for president in 2008 and his campaign launched the Tea Party movement and pioneered non-traditional fundraising methodology which has been adopted by other insurgent campaigns since then. Paul is a conservative libertarian politically who believes in minimal government and strict adherence to the Constitution and for his outspoken, sometimes irascible style.
Mitt Romney is a perceived frontrunner, but he has been running a very low profile campaign and losing ground to more active candidates. The former governor of Massachusetts has a strong business background and a successful record in office. He ran for president in 2008 and has high name recognition, but is somewhat tainted by his association with President Obama's public health care plan which was largely based on a plan Romney instituted in Massachusetts which has been plagued by budget overruns. This debate is Romney's opportunity to confirm that he is a frontrunner or end his campaign quickly with a bang.
Michelle Bachmann is a controversial Congresswoman from Minnesota who is best known for her association with the Tea Party movement and her extreme religious views which include strong opposition to gay rights and a call for a federal ban on pornography. Bachmann has a strongly fiscally conservative record and was a top contender in the polls until a few weeks ago when her numbers dropped into the single digits, possibly because of the entry of Rick Perry into the race and his appeal to the same demographic.