Sen. Paul Sarbanes (D), the longest-serving Senator in Maryland history, is expected to announce this afternoon that he will not seek a sixth term in 2006, sources said.

Sarbanes has scheduled a news conference for 1 p.m. in downtown Baltimore to announce his political plans.

Jesse Jacobs, Sarbanes’ spokesman, would not comment on what the Senator plans to say.

“You can find out at 1 o’clock,” Jacobs said.

But several sources in Washington, D.C., and in Maryland said they expected the 72-year-old Senator to announce his retirement, setting up what is certain to be a wild and crowded Democratic primary to replace him.

Potential Democratic candidates include former NAACP President Kweisi Mfume, Baltimore Mayor Martin O’Malley, and Reps. Albert Wynn, Chris Van Hollen and Benjamin Cardin.

Republicans would likely try to pressure Lt. Gov. Michael Steele into the race.

— Josh Kurtz