Sen. Joe Donnelly (D-Ind.), left, receives an endorsement from the Indiana Fraternal Order of Police and its president Bill Owensby, right.

Indiana’s largest law enforcement officers organization endorsed Sen. Joe Donnelly (D-Ind.) Monday in the state's pivotal U.S. Senate race.

The Indiana Fraternal Order of Police calls Donnelly one of its strongest advocates in Congress.

It’s been several election cycles since the Indiana FOP endorsed a candidate in a U.S. Senate race. State FOP President Bill Owensby says his organization decided to back Joe Donnelly this year because it believes in the mantra: “support your friends and defeat your enemies in Congress.”

"Senator Donnelly has been very vocal and outspoken," Owensby says. "He’s reached out to us on several occasions to talk about legislative issues before we’ve had a chance to reach out to him. And that resonates with us."

Donnelly authored legislation passed this year that helps provide mental health resources for law enforcement.

“My pledge to Bill and to the state FOP was I’ll have your back because you have our back," Donnelly says.

The Indiana FOP represents more than 19,000 officers statewide.