UPDATE: Bill Ladson of MLB.com tweets the Diamondbacks have told the Nationals that Gerardo Parra is unavailable. A source told Ladson that he expects Washington's center field solution to come from within the organization (likely meaning Bryce Harper).
Rumors of the Nationals' interest in Parra originally surfaced over three weeks ago, but no word of progress had emerged until today.
Though he put up good offensive numbers (292/.357/.427) for the Diamondbacks last year and earned a Gold Glove in left field, Parra is without a starting job for 2012. Parra is currently behind Jason Kubel in the Arizona depth chart.
If the Nationals do move to trade for Parra or anyone else to play center, it will likely create a logjam in the outfield midway through the season.
Adam Kilgore of the Washington Post reports that top prospect Bryce Harper--who was optioned to Triple-A this afternoon--will play predominantly center field at Triple-A Syracuse to start the season, and likely move into center for the Nats sometime during the season.