WASHINGTON — On Thursday, Rep. Trey Gowdy, R-S.C., was under more pressure than ever to justify his committee’s focus on former Secretary of State Hillary Clinton and her role in the Sept. 11, 2012, attacks in Benghazi, Libya, that killed a U.S. ambassador and three other Americans.

It showed.

Gowdy, who had said in an interview that these have been the “worst weeks of my life,” wasted no time in defending the committee’s credibility. It came in his opening statement.

“Madam Secretary, not a single member of this committee signed up to investigate you or your email,” Gowdy said in remarks that began what would be an 11-hour marathon.

“We signed up to investigate and therefore honor the lives of four people that we sent into a dangerous country to represent us.”

But the tension never faded between Gowdy and his Democratic committee members.

The former federal prosecutor frowned and looked at the ceiling in irritation when the ranking Democrat, Elijah Cummings, D-Md., accused the committee of passing up chances to interview other government officials in order to focus on Clinton herself.

Gowdy used every opportunity he could during the subsequent hours to counter allegations that his investigation has partisan motives – criticism that intensified in recent weeks as members of his own party applauded the committee for sinking Clinton’s poll numbers.

Indeed, Gowdy took pains at every turn to justify the probe. After Clinton gave an account of how four Americans lost their lives in the attacks, seeming to catch the Republican members off guard, Gowdy thanked her for pointing out their heroism. Then he used the moment to justify the money spent on his 17-month investigation.

“Frankly, it infuriates me to hear folks to my left who don’t raise a single whisper about spending $50 million to train five anti-ISIS fighters, but God forbid we spend one-tenth of that to give some answers to the family members sitting in the first row,” he said.

For their part, committee Democrats used every opportunity to bring up what Gowdy’s committee has spent – according to their website, $4,809,839 as of Thursday afternoon.

Compared to other Republican members of the committee, Gowdy was markedly restrained in his interactions with Clinton. He gave her the unusual option of avoiding the public swearing-in before the hearing.