Armas and Ortiz were part of Washington's rotation in 2006. Armas, 28, was 9-12 with a 5.03 ERA last season. One positive for Armas was that he didn't have any shoulder problems for the first time since 2002. He had a forearm problem in June, but he considered that a bump in the road.
Ortiz, 33, was the Nationals' top starter in 2006, going 11-16 with a 5.57 ERA. His best game was against the Cardinals on Sept. 4, when he came within three outs of throwing the team's first no-hitter. Ortiz also hit a solo home run in the game.
Despite being inconsistent on the mound, Ortiz often was praised for his work ethic and positive attitude.
Ortiz said last November he would love to stay in Washington because he wants to be close to his family in New York.
"Let me tell you: I love Washington. I love all the players," Ortiz said. "I told my agent that I want to come back to Washington. Right now, I want to know what Washington has for me. We have a lot of friends there."
Trachsel, 36, is a pitcher who is familiar with Nationals manager Manny Acta. The two worked together for two years when both were with the Mets. Trachsel is considered an innings eater. Last season, Trachsel went 15-8 with a 4.97 ERA in 164 innings for New York.
Trachsel also has spent time with the Cubs, Devil Rays and Blue Jays during his career. He has a record of 134-143 with a 4.28 ERA in 14 big-league seasons.
Sosa, 29, was a combined 3-11 with a 5.42 ERA with the Braves and Cardinals last year. If he goes to Washington, the Nationals are hoping Sosa can duplicate the season he had in 2005, when he went 13-3 with a 2.55 ERA with Atlanta.
Williams, 25, once was considered a top prospect in the Giants organization, but shoulder and elbow injuries hampered him in 2004 before he was traded to the Cubs during the 2005 season.
Williams spent last season in the Cubs and Athletics organizations. He appeared in five Major League games in '06 and gave up 10 runs in 12 1/3 innings.