The Nationals and Oakland Athletics, who discussed a potential trade for first baseman Nick Johnson all the way back in November, have revived those talks in recent weeks, according to a source familiar with the discussions. At one point last week, the source said, a deal seemed very close. Johnson is in the final year of a three-year, $16.5 million contract that will pay him $5.5 million this season. It is unclear what players the A's would be willing to give up for Johnson, but the Nationals have shown previous interest in 23-year-old first baseman Daric Barton, and a deal centering upon Johnson and Barton would make sense for both sides.