RENTON, Wash. -- The Seattle Seahawks are signing free-agent quarterback Sean Mannion, a source told ESPN's Adam Schefter on Saturday.

The signing adds apparent competition for one of the backup jobs behind Russell Wilson and reunites the 29-year-old Mannion with new Seahawks offensive coordinator Shane Waldron. Waldron was an assistant with the Los Angeles Rams for two of the quarterback's four seasons with the team.

The Seahawks have had Danny Etling and Alex McGough as their third and fourth quarterbacks behind Wilson and Geno Smith, who has served as Wilson's backup the past two seasons. The Seahawks typically keep two quarterbacks on their 53-man roster and another on their practice squad, though they began carrying another backup on their practice squad late last season as COVID-19-related insurance.

The Seahawks re-signed Smith this offseason to a one-year, minimum-salary deal worth $1,212,500, with $137,500 guaranteed.

Mannion entered the NFL as a third-round draft pick by the Rams out of Oregon State in 2015. He spent his first four seasons with the Rams and the past two with the Minnesota Vikings. He has appeared in 13 games (none last season) with two starts and has completed 45 of 74 passes for 384 yards and zero touchdowns with three interceptions.