Two high-ranking Congressional staffers, one a Senate Democrat and a House Republican, are leaving Capitol Hill after long political careers.

James Ryan, a top floor aide to Senate Minority Whip Harry Reid (D-Nev.), has signed on with banking giant Citigroup as a vice president. Ryan was hired by Nicholas Calio, a former Bush White House aide who recently joined Citigroup himself. Calio has been searching for a senior Democratic lobbyist.

A D.C. native and onetime news aide for The Washington Post, Ryan has worked for Reid since 1992, serving in a variety of jobs, including legal counsel and legislative director. Ryan has served as Reid’s top floor aide since 2000.

The 38-year-old Ryan graduated from Loyola College in Baltimore in 1987 with a bachelor’s in theology and political science. Ryan later was awarded a law degree from Catholic University.

“His political, policy and legislative skills are matched only by his ability to also reach out and connect with those around him,” said Reid. “He will be greatly missed.”

Over on the House side, David Marventano, staff director at the powerful Energy and Commerce Committee, announced Wednesday that he will leave Capitol Hill to take over the Washington office of Fluor Corp.

Marventano leaves the panel after more than two years as the committee’s top aide on issues ranging from telecommunications and energy to environment and health care.

He joined the Energy and Commerce Committee in January 2001 when Rep. Billy Tauzin (R-La.) took over the committee. Prior to that, Marventano served as a top lobbyist for the Securities Industry Association and as chief of staff to then-Rep. Bill Paxon (R-N.Y.).

Fluor, a Fortune 500 engineering, construction and procurement giant, tapped Marventano to help “build a larger team in Washington,” Marventano said.

Tauzin has not announced who will replace Marventano as staff director at the powerful committee. But Ken Johnson, the communications director, will add deputy staff director to his title.