Rep. C.A. "Dutch" Ruppersberger (search) bowed out of the 2006 Senate race Wednesday, only a month after setting up a committee to explore a possible bid to succeed retiring Sen. Paul Sarbanes (search).

Ruppersberger's decision narrows the field of Democrats to three possible candidates and one definite contender.

"There's a lot to do in the field I'm working in," said Ruppersberger of his decision to stay in the House. "When you love your job and you think you're helping your constituents," there is no reason to leave it, he said.

State Democratic officials praised Ruppersberger's qualifications, but said they were not worried about his decision to drop out, calling the remaining candidates "an incredibly strong roster."

"He (Ruppersberger) put a lot of thought into making the decision and he decided to do what is right for him," said Derek Walker, spokesman for the Maryland Democrats.

"It is a win-win," Walker said, calling Ruppersberger a national leader on homeland security because of his position on the House Select Committee on Intelligence.

"We are glad we have so many good candidates considering the race," he said.

So far, the only hopeful to officially declare his candidacy is Kweisi Mfume (search), the former president of the National Association for the Advancement of Colored People (search) and a former Baltimore congressman. Maryland Democratic Reps. Chris Van Hollen (search), Elijah Cummings (search) and Benjamin Cardin (search) have all said they are weighing Senate bids.

Ruppersberger joins fellow Democratic Reps. Albert Wynn of Mitchellville and Steny Hoyer of Mechanicsville, who have said the will not run. Baltimore Mayor Martin O'Malley and Montgomery County Executive Doug Duncan, the other leading Democrats mentioned, have both insisted that they are focused on a 2006 race for governor.

But Ruppersberger agreed with Walker that state Democrats are "fortunate to have a deep bench of highly qualified potential Democratic candidates for Senate."

State Republican officials said the list of candidates, while long, was not promising.

"There is still a long line of liberal Democrats jockeying and salivating for the chance to replace Sen. Sarbanes. We think that long line of contenders does not represent the values of the people of Maryland," said Maryland GOP spokeswoman Audra Miller, reciting a prepared statement for the party.

Cardin issued a statement praising Ruppersberger's service in the House, and saying he respects and understands the decision to stay in the House. Cummings' staff reiterated that he was still considering a bid, but would not have any comment on the race until he came to a decision.

Neither Van Hollen nor Mfume could be reached for comment Wednesday.

Mark Plotkin, political commentator for WTOP radio in Washington, said that Ruppersberger's decision was understandable.

"Why give up your House seat to lose for a higher office?" Plotkin asked. "I think he saw the cards on the table. He was fourth in four-person race."

Capital New Service's Megan McIlroy contributed to this story.