A federal grand jury indicted Rep. Chaka Fattah of Pennsylvania and four associates on racketeering conspiracy charges, accusing them of misusing hundreds of thousands of dollars in taxpayer, charity and campaign funds.

The charges are the culmination of a long-running Federal Bureau of Investigation probe of Mr. Fattah, a 58-year-old Democrat who represents Philadelphia. Many of the charges stem from Mr. Fattah’s failed bid to win the nomination for mayor in 2007.

Mr. Fattah, first elected to Congress in 1994, serves on the appropriations committee overseeing the Justice Department’s budget. Democratic leaders said he would step down from the panel while the case proceeds.

Leslie Caldwell, head of the Justice Department’s criminal division, said Mr. Fattah and his associates “embarked on a wide-ranging conspiracy involving bribery, concealment of unlawful campaign contributions and theft of charitable and federal funds to advance their own personal interests.” The charges are included in a 29-count indictment filed in Philadelphia.

Mr. Fattah denied wrongdoing and said he plans to keep working in Congress.