Democrats have signed up their candidate in the race for Vice President Joe Biden's former Senate seat.

New Castle County Executive Chris Coons announced Wednesday that he will run for the open Delaware seat, which Biden's son Beau passed on last week. If Coons wins his party's nomination, he will likely face Rep. Mike Castle (R-Del.), who is an early favorite for the November general election.

“Before I was elected in 2004, the county government was mired in scandal," Coons said in a statement. "I want to take my strong track record of getting real results to the U.S. Senate because the people of Delaware deserve leadership that represents their values.”

A Research 2000 poll for the liberal website Daily Kos in October showed Castle leading Coons 51-39. Rasmussen last week put Castle up 56-27. Polling generally shows Castle, a former governor, remains popular in the state.

Democrats have made assurances that they will contest the race and have said Coons is a sleeper. Democratic Senatorial Campaign Committee Chairman Bob Menendez (N.J.) hailed Coons's entry Wednesday.

"Chris Coons has an impressive record of shaking up government, cutting wasteful spending, and working with local businesses to create jobs," Menendez said. "With Chris's entrance into the race, Delawareans will face a choice between a proven reformer who has created an engine of economic growth and a longtime Washington insider who has voted with the special interests."

The vice president on Tuesday said Coons will be a force to be reckoned with in the race, which some declared a loss for Democrats after Beau Biden opted not to run.

"I predict to you that Chris Coons is going to surprise the devil out of them," Joe Biden told MSNBC.