James Mackler, a Nashville attorney and Iraq War veteran, will on Monday become the first Tennessee Democrat to announce plans to run in 2018 for the state's U.S. Senate seat held by U.S. Sen. Bob Corker, R-Tennessee.

Mackler cited his military background repeatedly in a news release provided to The USA Today Network - Tennessee ahead of the formal announcement, saying he's "running to restore respect, honesty, and most importantly, integrity in Washington."

“Our country has become so divided that our leaders refuse to work together to solve our most important problems," Mackler said in a statement. "As a veteran, I know first hand the strength of teamwork, cooperation, and the benefits of diversity to accomplish even the most difficult mission."

Mackler, 44, recently practiced law at Frost Brown Todd LLC and Bone McAllester Norton, PLLC, both in Nashville.

Before those stints, Mackler spent three years as a Blackhawk helicopter pilot with the 101st Airborne Division, according to a news release from his campaign, after he had put aside his legal work for the Army in 2001 following the attacks on 9/11. His military service included a deployment to Iraq.

Mackler, who continues serving in the Tennessee Air National Guard, earned his Parachutist Badge, Combat Action Badge and an Air Medal for "bold and audacious piloting." After his service in Iraq, Mackler transferred to the Judge Advocate General Corps.

Mackler would be a major underdog in the November general election if he prevails in next year's Democratic primary for the seat. In politically red Tennessee, Democrats haven't fielded a competitive Senate candidate since 2006, when U.S. Rep. Harold Ford Jr. lost to Corker.

Corker, Tennessee's junior U.S. senator, defeated Democrat Mark Clayton, a political unknown, in 2012 for his first reelection. It was an embarrassing race for the Tennessee Democratic Party, which disavowed Clayton's candidacy because of his association with an anti-gay hate group and for an uneven record of voting in Democratic primaries.

Corker, who chairs the powerful U.S. Senate Committee on Foreign Relations, hasn't formally announced intentions to run for a third-term in his seat, but most observers expect him to do so. Some have speculated Corker could decide to run for governor of Tennessee next year — a scenario that's considered an outside possibility but one that Corker still hasn't rejected.

In a statement on his run, Mackler said true leadership comes from a sense of duty and "an obligation to protect and work for the benefit of others." He said best results are accomplished when people recognize the value and contributions of each other.

"True leaders hold themselves and others accountable," Mackler said. "These are values that I learned serving my country and will continue to carry as Tennessee’s next U.S. Senator.”