Democrats in the US House of Representatives are considering whether to participate in a Republican investigation into the attack on the US consulate in Benghazi, Libya, in 2012.
Democrats may boycott the panel or send just one of their allotted five members.
Republicans argue the Obama administration misled the public on the nature of the attack in which four Americans including Ambassador Chris Stevens were killed.
The inquiry was approved by a vote of 232-186 on Thursday.
House Minority Leader Nancy Pelosi called the panel a "political stunt".
''We've been there, done that. Why are we doing this again?," Ms Pelosi said on Friday, referring to seven previous inquiries.
She said the party is currently weighing whether it will abstain from the panel, send a single representative or fill the five seats allotted to Democrats.
Staff were also negotiating more equal terms for Democrats.
The BBC reports the attack on 11 September, 2012, when gunmen stormed the US compound and set it on fire, is a political lightning rod.
Previous inquiries blamed the State Department for inadequate security at the embassy.
Republicans have been very critical of then-Secretary of State Hillary Clinton, who is now considering a 2016 presidential run.