State Senator Jeff Smith of St. Louis has pleaded guilty to two federal charges of conspiracy to obstruct justice and has resigned his Senate seat.

Smith was charged with obstructing a Federal Elections Commission investigation into election law violations in Smith’s 2004 congressional campaign. The other charge accused him of obstructing a federal grand jury investigation earlier this year.

He says he authorized a friend to raise money for an anonymous flier campaign against Russ Carrnahan who beat Smith and several others for the Democratic nomination and went on to win the general election. Carnahan’s campaign filed a complaint with the FEC.

Smith was elected to the Senate in 2006.

Also implicated in Representative Steve Brown of St.Louis, whose attorney says will plead guilty to similar charges.

The federal sentencing guidelines say both men could face 15-21 months in prison.