The Seahawks took care of one of their biggest off-season priorities by signing Marshawn Lynch to a long-term deal. / Drew Sellers, Sportspress Northwest

A major deed on the Seahawks’ off-season to-do list was done Sunday night when leading rusher Marshawn Lynch was signed to a deal that, according to multiple media sources, is potentially worth $31 million over four years, with $17 million guaranteed.

The Seahawks were up against an NFL deadline Monday for placing franchise tags on players. But the tags are for a single year and both sides wanted more contract length. If the Seahawks did not reach a deal at all, he would have been an unrestricted free agent March 13.

“We are excited to keep Marshawn as an important part of what we are building,” general manager John Schneider said in a club release. “This is what we were hoping for when we acquired him from Buffalo.”

Lynch, 25, has been the most productive running back since Shaun Alexander’s 2005 season helped the Seahawks to the Super Bowl. In 2011, Lynch had career highs in rushing yards (1,204) and touchdowns (13) and also scored in a club-record 11 consecutive games. That broke by two Alexander’s mark, also in ’05. Lynch, also had 100-yard totals in six of the final nine games to spark a second-half surge that helped the seasons to a 5-3 record in the second half.

An alternate to the Pro Bowl, Lynch was added to the NFC roster as an injury replacement and rushed for a team-high 43 yards on eight carries.

Lynch ran for 573 yards and six touchdowns in 12 games in 2010 after coming over in the trade with the Bills.who was obtained in a trade with the Bills on Oct. 5, 2010. In the playoff game that year against New Orleans, his “Beast Quake” 67-yard touchdown run became one of the most memorable games in Seahawks history.