The Obama administration faced increased pressure Thursday to provide more information about the attack on the U.S. Consulate in Libya that left an ambassador and three other Americans dead.

Senate Foreign Relations Committee Chairman John Kerry (D-Mass.) was circulating a letter Senate aides said would be signed by members of both parties asking for more information and another briefing on Libya — a development Republicans described as a significant shift from what had been a partisan fight.

“It’s my understanding today that all members of the Foreign Relations Committee — both Democrats and Republicans — are asking the administration for answers,” Sen. Bob Corker (R-Tenn.) said. “So this is now something that certainly could never be colored as partisan.”