WASHINGTON - Democratic National Committee Chairman Howard Dean plans to step down from his post when his term expires in January, wrapping up a tenure in which the party heavily invested in all 50 states for a payoff that helped elect Barack Obama president.

Dean, who was briefly his party’s presidential front-runner in 2004, was elected DNC chairman in 2005 and has long vowed to serve only one, four-year term. At a postelection news conference in Washington last week, Dean indicated again that he didn’t plan to stay on, aides said today.