Dec 20, 2007 8:47 AM EST

The Philadelphia Phillies and free agent outfielder Geoff Jenkins have reached preliminary agreement on a two-year deal believed to be worth about $13 million, a baseball source told ESPN.com.

The agreement includes a third year vesting option based on plate appearances that could increase Jenkins' total package to $20 million, the source said. The deal could be announced as early as Thursday.

Jenkins, 33, is a .277 career hitter with 212 home runs in 10 seasons with the Milwaukee Brewers. He became a free agent when the Brewers declined his 2008 option of $9 million after the season.

The Phillies, who lost Aaron Rowand to San Francisco through free agency and sent Michael Bourn to Houston in a trade for closer Brad Lidge in November, have been looking for a left-handed bat to share time with Jayson Werth in right field.

Via ESPN