WASHINGTON — Four weeks before the election, Republicans used a politically charged House hearing to confront State Department officials about security at the U.S. consulate in Libya and assail the Obama administration’s early response to the killing of the ambassador and three other Americans there.

GOP lawmakers refused to accept the department’s explanation Wednesday that protection judged adequate for the threat was overwhelmed by an unprecedented assault in Benghazi on the 11th anniversary of the Sept. 11 terror attacks.

They also rejected Under Secretary of State Patrick Kennedy’s explanation that officials were relying on the best intelligence available in characterizing the attack afterward as stemming from a protest over an anti-Islam Internet video rather than a deliberate, planned act of terrorism.

A State Department official acknowledged that she had declined to approve more U.S. security as violence in Benghazi spiked, saying the department wanted to train Libyans to protect the consulate.

“I made the best decisions I could with the information I had,” said Charlene R. Lamb, a deputy assistant secretary for diplomatic security.

U.S. Ambassador Chris Stevens and three other Americans, including two former Navy SEALs, were killed in what administration officials now describe as an act of terrorism.

In statements immediately after the attack, neither President Barack Obama nor Secretary of State Hillary Clinton mentioned terrorism. And both gave credence to the notion that the attack was related to protests about the privately made anti-Islam video.