The Nationals are expected to hold a news conference at Nationals Park on Thursday. General manager Jim Bowden was not immediately available for comment. He was believed to be flying from Viera, Fla., to Washington on Wednesday night to attend the news conference.
"The opportunities [as a free agent] weren't exactly what I wanted them to be, but I get a chance and hopefully turn the program around," Dunn said on the MLB Network. "I think it will be a better feel of accomplishment to help turn the program around than go [to a place] that is established."
Dunn, 29, and Bowden have a history together with the Reds organization. Bowden drafted Dunn in the second round of the 1998 First-Year Player Draft. Three years later, Dunn was in the big leagues and became Cincinnati's best power hitter.
Dunn will also be reunited with his best friend, outfielder Austin Kearns, who said back in November that Dunn would be a great addition to the Nationals.
"Everybody likes the power and he walks," Kearns said. "He is just a presence in the lineup. You know he is going knock in his runs. You don't have to worry about that. He has stayed healthy, so he is going to be in there every day."
Dunn, who will join Ryan Zimmerman in the middle of the lineup, has hit at least 40 home runs in each of the past five seasons. While he has just a .247 career batting average, he has a .381 on-base percentage and can play both left field and first base.
With the Nationals, however, Dunn will bat cleanup and be the everyday first baseman, replacing Nick Johnson. There are two drawbacks to Dunn's game. He strikes out a lot and is considered a below-average defensive first baseman and outfielder.
The Nationals have been looking for a left-handed slugger since the 2008 season ended. Their top choice was switch-hitting first baseman Mark Teixeira, but signed with the Yankees in December.
The team then targeted Dunn, and it seemed both sides reached a stalemate by mid-January. It was reported that Dunn exceeded Washington's price range, and it appeared that the Dodgers and Angels may have had the inside track to acquire Dunn. But things started to heat up between Dunn and the Nationals in the past week.
The acquisition of Dunn means that Washington mostly likely will make additional moves. The team has been trying to trade Johnson, who is not likely to accept a bench role. There was talk of the Athletics having interest in Johnson after the team asked for his medical records.
Johnson is a talented player, but the Nationals grew frustrated because he is often injured. Over the past two seasons, Johnson played in just 38 games. A broken leg forced him to miss the entire 2007 season, and he saw limited action last year because of a wrist injury.
First baseman Dmitri Young remains on the team as a non-roster player. On Tuesday, team president Stan Kasten talked about Young as a quality player off the bench. Young is trying come back from one of the toughest seasons of his career. Injuries and diabetes limited him to only 50 games in 2008.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.