State Treasurer Dean Martin has called it quits in the governor's race.

That leaves Gov. Jan Brewer with just one credible opponent: Businessman Buz Mills, who has spent more than $3 million on his effort to unseat Brewer.

Martin's letter:

It has been an honor to serve the people of Arizona. Public service takes dedication and many long hours to accomplish the business of the people who elected us. I am humbled to have had the support of the people for these past 10 years.

Elected office was never my intended career path; I am a small business owner who was drafted to run for the Arizona State Senate and then later Arizona State Treasurer. I am proud of my service and I am forever grateful for the support you have given me over the years. I especially want to thank my friends and colleagues who stood by my side last year during the tragic death of my wife Kerry and my son Austin. I will never forget your support.

Today, I am announcing that I am suspending my campaign for Governor of Arizona. During a time when the Obama Administration has filed

a frivolous lawsuit against our great state, a budget deficit is looming, and our economy is still shaky, I feel a contested primary would be a distraction. While a serious debate about the fiscal condition of our state is needed, the heavy hand of the Obama Administration will not allow this debate to continue. I fully intend to support the Governor in her battle with the Obama Administration and its relentless attack on the people of Arizona.

In that regard, I urge the Governor to file suit against the Federal Government for the costs of not securing our border. Earlier this year I sent former Arizona Governor and now Homeland Security Secretary Janet Napolitano a bill for one billion dollars of uncompensated costs due to incarceration of illegal immigrants who have committed felonies in Arizona. This is a good start and trust the Governor will follow through. As a state we need to stand together to fight the overreaching federal government that has failed to secure our border with Mexico.

I want to thank the countless volunteers who have been part of this campaign since January. Their dedication to the campaign and Arizona is second to none. But our state and the residents of Arizona are more important than playing politics. The Obama Administration's lawsuit is a blatant attempt to divide us and I will not be part of the problem; rather I intend to be part of the solution. Attorney General Terry Goddard, is not willing to enforce our laws and is instead playing the role as Obama-defender-in-chief. I got into this race because I did not want to see Goddard become Governor. This is still my goal, and is the reason I have made this decision to suspend my campaign.

Governor Brewer is going to need all our help to shoulder the burden of defending Arizona from the federal government. It is our duty to stand together as Arizona residents against an intrusive federal bureaucracy.

While my service to this state as an elected official will come to an end in December, I will continue to serve in other ways. After taking some much needed time off, I will be focusing my efforts on the charitable foundation we established, MartinCharities.org to continue my late wife Kerry's spirit of service to the community in water safety and financial literacy.