PHILADELPHIA -- If the Nationals decide not to sign first baseman Adam Dunn to an extension, here is a look at the first basemen the team could have interest in during the offseason, according to sources.

Carlos Pena, Rays: He is on the top of their list, but one has to wonder if he's worth a lot of money. He has had a regular season to forget, hitting .196 while striking out almost as much as Dunn. Pena is considered a "character guy" and an above-average defender at first, something the Nationals want.

Aubrey Huff, Giants: An average defensive first baseman, Huff, 33, was arguably the Giants' MVP during the regular season, hitting. 290 with 26 home runs with 86 RBIs.

Paul Kornerko, White Sox: He's 34 years old and still has a lot left in the tank. This past season, he hit .312 with 39 home runs and 111 RBIs. He is a free agent, but some in the Nationals organization believe that he will return to the White Sox.

Adam LaRoche, D-Backs: He has a mutual option with the club. If he becomes a free agent, look for the Nationals to have interest in him. LaRoche had his best season of his career in 2010, driving in 100 runs for the first time.

James Loney, Dodgers: If he is available in a trade -- some in the Nationals organization believe that he could be -- look for Washington to go after him hard. He has been a consistent hitter the past three seasons with the Dodgers, averaging 12 home runs and 89 RBIs. One problem: whenever a trade is involved, look for opposing teams to ask for shortstop Ian Desmond or right-hander Jordan Zimmermann.

Josh Willingham: If the Nationals can't acquire a first baseman, look for them to have Willingham at the position. During his career, Willingham has played three games at the first base -- one with the Nationals and two with the Marlins.

If the Nationals settle on Willingham at first, look for them to focus on getting an outfielder. The team has interest in Phillies right fielder Jayson Werth, who is a free agent after the World Series.

Werth is familiar with Nationals manager Jim Riggleman, who was a bench coach when both were with the Dodgers.