The US House of Representatives has held Attorney General Eric Holder in criminal contempt of Congress for failing to provide documents related to a failed gun-tracking operation.
It is the first time a sitting Cabinet member has been held in contempt.
The vote was 255-67, with more than 100 Democrats boycotting. They said the contempt resolution was a political stunt.
Republicans accuse Holder, the top US lawyer, of stonewalling the investigation of "Operation Fast and Furious," in which guns purchased in the United States were taken to Mexico.
Democrats claim the vote was politically motivated ahead of the November election in which their leader President Barack Obama is seeking a second term.
The vote on a criminal contempt resolution sent the matter to the US attorney for the District of Columbia, who serves under Holder. In previous contempt cases, federal prosecutors in the US capital have refused to act on congressional contempt citations against members of their own administration.
African-American politicians led a walkout as members filed up the aisle and out of the chamber to protest the action against Holder, who is the nation's first black attorney general. Democratic leader Nancy Pelosi joined the boycott, saying Republicans had gone "over the edge" in their partisanship.
Seventeen Democrats voted with Republicans in favour of the contempt vote, while two Republicans joined other Democrats in voting No.
A separate vote on civil contempt passed 258-95. It will allow the House to go to court in an effort to force Holder to turn over the documents. In past cases, courts have been reluctant to settle disputes between the legislative and executive branches.
The National Rifle Association, a gun advocacy group, pressed hard for the contempt resolution, leaning on members of both parties who want to stay in the NRA's good graces. Holder said afterwards the vote was merely a politically motivated act in an election year.