David Axelrod

A Chicago political consultant and a former journalist, Axelrod is Barack Obama's chief campaign strategist. He previously helped shape the Senate campaigns of Hillary Clinton (D-N.Y.), John Edwards (D-N.C.) and Chris Dodd (D-Conn.).

Cassandra Butts

She is Barack Obama's domestic policy adviser, close friend and former classmate at Harvard Law School, '91. Before working on Obama's 2008 presidential campaign, Butts served as senior vice president for domestic policy at the Center for American Progress and was a senior adviser to Rep. Richard Gephardt (D-Mo.).

Tom Daschle

Former Senate Majority Leader Tom Daschle got to know Barack Obama during their 2004 Senate campaigns. After losing his election, many Daschle staffers went to work in Obama's office, including his former chief of staff. In 2006, Daschle advised Obama not to miss the window of opportunity in 2008 to make a run for the presidency.

Lindsey Graham

Graham, South Carolina's senior senator, has traveled with McCain on the campaign trail and has been in "many scrapes" with the Arizona senator on such controversial issues as detainee policy, campaign finance, immigration and the war in Iraq. The two were part of the "Gang of 14," which negotiated a bipartisan compromise to avert the filibuster of judicial nominees.

Mark Halperin

Editor-at-large and senior political analyst for Time magazine, Halperin previously worked at ABC News for nearly 20 years, covering five presidential elections and serving as political director from 1997 to 2007. He is the author of The Undecided Voter's Guide to the Next President (2007) and co-author of The Way to Win: Taking the White House in 2008.

David Mendell

Mendell covered Obama's early career as a political reporter for the Chicago Tribune. He is the author of the 2007 biography Obama: From Promise to Power.

Pete Rouse

Rouse became Barack Obama's chief of staff in 2005, after serving in the same role for Senate Majority Leader Tom Daschle. A congressional staffer since 1971, Rouse's power has led to him being nicknamed "the 101st senator."

Mark Salter

Salter has worked for John McCain since 1988, starting as a legislative aide and then becoming his counselor and speechwriter. He has co-written five books with Sen. McCain, including his memoirs, Faith of My Fathers and Worth the Fighting For.

Orson Swindle

Swindle has remained friends with John McCain ever since the two met in a Hanoi prison in 1970. He is an adviser to McCain's campaign and spoke at the 2008 Republican National Convention.

John Weaver

He was McCain's longtime aide and chief strategist until July 2007, when McCain ordered a shakeup in his troubled campaign.