The House Benghazi committee's Republican chairman is ignoring statements by his own former lawyer indicating that the U.S. military acted properly on the night of the deadly Sept. 11, 2012, attacks in Libya, the panel's Democrats said.

Reps. Elijah Cummings and Adam Smith said Rep. Trey Gowdy, R-S.C., omitted the lawyer's comments when he fired back at the Defense Department for criticizing the GOP-led investigation into the attacks that killed four Americans.

Gowdy's actions, coupled with delays that have pushed the 2-year-old inquiry into the heat of the 2016 presidential race, "have damaged the credibility of the Select Committee beyond repair," Cummings and Smith wrote Sunday in a letter to Gowdy.

The Associated Press obtained a copy of the letter.

Cummings of Maryland is the senior Democrat on the Benghazi panel; Smith, of Washington state, is the senior Democrat on the House Armed Services Committee. He also serves on the select Benghazi panel.

The criticism by the two Democrats is the latest volley in an escalating, election-year fight over the Benghazi panel's actions. The panel, created in May 2014, has not conducted a public hearing since October, when former Secretary of State Hillary Clinton testified.

Democrats call the panel a thinly veiled excuse for Republicans to criticize Clinton, the front-runner for the Democratic presidential nomination. Republicans say the Obama administration has dragged its feet, failing to produce needed documents or interview subjects, delaying a final report.

U.S. Ambassador Chris Stevens was among those died during the twin assaults nearly four years ago. Previous investigations blamed management failures at the State Department for a lack of security at the U.S. diplomatic mission in Benghazi, an issue that has dogged Clinton and other Obama administration officials.

Cummings and Smith cite comments by retired Army Lt. Gen. Dana Chipman, who served as chief counsel for Republicans on the Benghazi panel from August 2014 until last January.

Chipman "repeatedly commended the military's actions on the night of the attacks during closed interviews with Defense Department officials," Cummings and Smith wrote.

Chipman, a former judge advocate general for the Army, attended a closed-door interview with former Defense Secretary Leon Panetta on Jan. 8.

Cummings and Smith quote Chipman as telling Panetta: "I think you ordered exactly the right forces to move out and to head toward a position where they could reinforce what was occurring in Benghazi or Tripoli or elsewhere in the region. And, sir, I don't disagree with the actions you took, the recommendations you made and the decisions you directed."

Chipman later told Panetta he was "worried" that U.S. officials were caught by surprise during the Benghazi raids, which occurred on the anniversary of the 9/11 attacks. Still, Chipman told Panetta: "Nothing could have affected what occurred in Benghazi," Cummings and Smith wrote.

The letter from the Democrats comes after Gowdy sent a letter to Defense Secretary Ash Carter complaining that a top Pentagon official had intentionally mischaracterized the House inquiry.

Gowdy said comments by Stephen C. Hedger, assistant secretary of defense for legislative affairs, were "riddled with factual inaccuracies" and did "a disservice to the public" and employees at the Defense Department.

Hedger, in an April 28 letter to Gowdy, expressed frustration with the Benghazi panel, citing a "crescendo" of costly, duplicative and unnecessary requests, including a few based on claims made on Facebook or talk radio.