PHILADELPHIA -- In need of a power hitter, the Nationals are in serious discussions about acquiring Rockies outfielder Preston Wilson.

According to The Sporting News, the Nationals would trade right-hander Zach Day and outfielder J.J. Davis to the Rockies for Wilson.

Nationals interim general manager Jim Bowden, who is on bereavement leave because of the passing of his grandmother, said via e-mail, "There has not been a trade completed with the Rockies."

One baseball source confirmed that the Nationals are working hard to acquire Wilson, but the two teams are trying to agree on dollar figures. Wilson is making $12.5 million this season, and the Nationals want the Rockies to pay most of it.

If the teams come to terms on a deal, Wilson can reject the trade, since the Nationals are on the list of teams he could refuse a trade to because the franchise was in Montreal when he signed his contract. But Wilson told Colorado reporters recently that he would accept a trade to the Nationals.

Bowden has said that the Nationals need another bat, and the club has been after Wilson for weeks. Entering Friday's action, the Nationals were last in the National League in home runs and RBIs.

Going into Friday's game, Wilson is hitting .258 with 14 home runs and 45 RBIs. His best season was in 2003, when he hit .282 with 36 home runs and 141 RBIs for the Rockies. Wilson is the stepson of former Major Leaguer Mookie Wilson.

If the Nationals acquire him, Wilson will play center field, not left, as was originally expected. Manager Frank Robinson believes his current center fielder, Brad Wilkerson, is wearing down, and the Nationals want to put Wilkerson back in left field.

During the offseason, Wilkerson prepared himself to play left field and hit for power in 2005. But during Spring Training, he had to lose 15 pounds to be in better shape to play center field.

"It would be a big help [to go back to left field]," Wilkerson said. "Center field takes a lot out of you. You run around a lot more, but I hope we can stay healthy enough where [playing left field] could happen."

As for Day and Davis, they don't figure to be in the Nationals' long-term plans. Day started the season in the rotation, but was demoted in early May after struggling.

Day is on the disabled list with a fractured right radius, but he is currently on a rehab assignment for Double-A Harrisburg. He has given up just two runs in eight innings.

Davis, who was obtained from the Pirates in an offseason trade, started with the Nationals as a reserve player, but he had problems hitting breaking balls and was demoted to Triple-A New Orleans in early May. He is hitting .282 with 12 home runs and 31 RBIs for New Orleans.

Stat of the day: Entering Friday's play, third baseman Vinny Castilla is hitting .350 (28-for-80) with three home runs and 18 RBIs while batting sixth. Anywhere else in the lineup, Castilla is hitting is 47-for-210 (.224).

Did you know? The Nationals are 22-22 when opponents score first.

On deck: The Nationals play the second game of a three-game series against the Phillies on Saturday afternoon at Citizens Bank Park.

Nationals right-hander John Patterson, who will oppose Cory Lidle, will face the Phillies for the second time this season. The last time he faced them was on April 26 in Washington. Patterson pitched 6 2/3 innings and gave up just one run on six hits. He struck out six and walked four. The Nationals won, 3-1.

In his last start, Patterson was solid for six-plus innings, giving up two runs on four hits against the Mets. He struck out seven and walked two. Patterson didn't figure in the decision as the Nationals lost, 5-2.