SEATTLE -- A fresh start for Marshawn Lynch. A rugged runner for Seattle's lagging ground game.

And a clear sign the rebuilding continues in Buffalo.

The Bills gave up on Lynch as their featured ball carrier on Tuesday, trading him to Seattle. That clears the way to give more playing time for Fred Jackson and first-round draft pick C.J. Spiller in the Buffalo backfield.

Buffalo will receive a 2011 fourth-round pick and a 2012 conditional pick, a Seahawks team source told ESPN NFL Insider Adam Schefter. The conditional pick is a sixth-round selection that can become a fifth-rounder based on Lynch's productivity with Seattle.

Seattle hopes Lynch provides a spark missing from its run game through the first four weeks.

"We bring a guy into the program that we think is going to give us a little boost," Seattle coach Pete Carroll said after practice Tuesday. "You know that we've emphasized trying to get this running game in order. We hope that he'll help in that regard. We're pleased to get that done. We'll move forward this week. It's good we're on a break. It doesn't disrupt a game week preparation and we'll get him in here as soon as possible and we'll get to work."

Seattle released running back Julius Jones, its leading rusher the past two seasons, to clear a roster spot for Lynch. Jones restructured his contract and took a hefty pay cut just before the start of the season, then carried the ball just 12 times for 30 yards and was inactive on Sunday against St. Louis.

Seattle's run game has struggled through four games, ranking 27th with 79.5 yards per game. In three games, the Seahawks were held below 80 yards rushing, putting more pressure on quarterback Matt Hasselbeck.

Without a clear No. 1 back, the Seahawks ran by committee before settling on the speedy Justin Forsett as the featured back the past two weeks. Forsett had a season-high 19 carries Sunday against St. Louis, but managed only 65 yards. Seattle hasn't seen a back approach 1,000 yards since Shaun Alexander was the league MVP in 2005 after running for 1,880 yards and 27 touchdowns in the Seahawks' NFC championship season.

Now Forsett and Lynch -- teammates at California -- are reunited in Seattle. Lynch was a groomsman at Forsett's wedding earlier this year.

"We're different backs but I think they complement it well. If you go back at Cal, we had a nice little one-two punch there and it's always exciting," Forsett said. "Any given moment, any one of us could break and it was pretty fun. We just have fun together."

The Seahawks (2-2) have a bye week following their 20-3 loss to St. Louis on Sunday. That gives Lynch time to get acclimated to Seattle's offense and potentially be on the field Oct. 17 when they play at Chicago.

"We're going to bring him in to play a lot," Carroll said. "We'll wait and see when we get him here but we're bringing him in here to play a bunch."

Also on Tuesday, Seattle re-signed offensive lineman Chester Pitts -- cut last week -- and released lineman Evan Dietrich-Smith.

Buffalo (0-4) lost to the New York Jets 38-14 and plays host to Jacksonville on Sunday, and Lynch's trade only highlights the much larger rebuilding job in front of the Bills.

Last week, coach Chan Gailey released former starting quarterback Trent Edwards, who is now with the Jaguars.

To replace Lynch on the active roster, the Bills promoted rookie Andre Anderson from their practice squad as their third running back. Anderson originally signed with the team in August to fill in after both Lynch and Jackson were injured. He had 2,009 career yards and 17 touchdowns at Tulane.

The release of Edwards and now Lynch's trade all point to this being a season of evaluation for the entire Bills roster after the team made few splashes in free agency this offseason and elected to rebuild through the draft.

"Marshawn has worked hard and played hard for us this season and we certainly appreciate his efforts," Bills GM Buddy Nix said in a statement. "We are constantly evaluating our personnel and feel that this is a good move for our team's future."

After losing his starting job to Jackson last season, Lynch reclaimed the job in Week 2 this year and led the Bills with 37 carries for 164 yards. In 45 career games, he has 2,765 yards rushing and 17 touchdowns, along with 670 yards receiving and a score.

The deal was made two weeks before the NFL trade deadline, and marks a turnaround in philosophy for the Bills, who said last spring they had no intention of trading him. Lynch had been seeking a fresh start after his reputation in Buffalo took a hit following his off-field troubles.

In June 2008, he pleaded guilty to a traffic violation and admitted to driving off after striking a female pedestrian with his car near Buffalo's downtown bar district.

In March 2009, Lynch pleaded guilty to a misdemeanor gun charge in Los Angeles, after police discovered a semiautomatic handgun in a backpack of the trunk of a parked car Lynch was sitting in.

Information from The Associated Press was used in this report.