House Select Committee on Benghazi Chairman Trey Gowdy said his panel is working to wrap up a months-long investigation of the 2012 terror attack before this summer, bucking Democratic predictions that the South Carolina Republican would attempt to drag the probe into the heat of election season.

But Gowdy said the committee would only be able to publish its final report if federal agencies comply with document requests that have collected dust for nearly a year.

"Our committee continues to break an immense amount of new ground as we compile the most comprehensive accounting of what happened before, during and after the terrorist attacks in Benghazi," Gowdy said in a statement Thursday. "As we approach our 80th witness interview and work to release our report and recommendations before summer, it's time for the administration to turn over the records this committee requested nearly a year ago."

Gowdy announced a slate of new witness interviews that will take place behind closed doors over the next week, bringing the total number of officials questioned in connection with the probe to 79.

That includes 62 witnesses who were never interviewed by another committee.

Upcoming witnesses include Gentry Smith, the former deputy assistant secretary for countermeasures, James "Sandy" Winnefeld, Jr., the former vice chairman of the Joint Chiefs of Staff, and an unnamed "eyewitness to the attacks from the national security community."

Gowdy's committee has faced intense criticism from Democrats who argue its investigation is nothing more than a duplication of the efforts of other committees that have looked into the Benghazi attacks in the more than three years since the violence.

The select committee was the first to uncover Hillary Clinton's use of a private email server early last year, although the probe has not focused on those emails since requesting copies of Benghazi-related messages from the State Department. The panel was also the first to ask for copies of emails written by and to Ambassador Chris Stevens, who was one of four Americans killed in the attack.