He covered the Supreme Court and the White House for the Star before moving to the Baltimore Sun, where he was the national political correspondent.

[6] In 1984, Barnes was chosen to be one of three panelists quizzing then-President Ronald Reagan and challenger Walter Mondale in the first nationally televised debate of the 1984 presidential campaign.

Barnes has made cameo appearances in the Hollywood films Dave, Getting Away with Murder, and Independence Day.

Reviewing it in The Washington Monthly, Isaac Chotiner called it "fawning and at times unintentionally amusing", revealing its author as a "perfect Bush hack".

In the days leading up to the 2008 United States election, Barnes was the only political pundit out of 27 catalogued by the Huffington Post (including Karl Rove, Alex Castellanos, Matthew Dowd, Ed Rollins, and George Will) to predict a John McCain victory for U.S. President (286 to 252 electoral votes).