Heisman Trophy winner and former first-round draft pick Matt Leinart has agreed to terms on a contract with the Buffalo Bills, a league source close to the negotiations confirmed to The News.

The emergency signing comes a day after Bills veteran Kevin Kolb suffered concussion-like symptoms after a blow to the head in the exhibition game at Washington. The Leinart agreement first was reported this afternoon by Mike Garofalo of FOX Sports.

Undrafted rookie Jeff Tuel is expected to start Thursday’s exhibition finale, and perhaps the regular-season opener if rookie first-round draft pick EJ Manuel can’t make a speedy recovery from knee surgery.

Leinart, 30, provides a veteran presence behind Tuel. Leinart’s six-year NFL career has been a disappointment after he enjoyed one of the most celebrated college quarterbacking careers ever at the University of Southern California. Besides winning the Heisman in 2004, Leinart helped USC to two national titles, in 2003 and 2004.

Leinart’s NFL career, however, never has gained traction. The Bills will be his fourth team. He is 8-10 for his career as a starter, and he has made only two starts in the last four seasons.

He was the 10th overall pick of the Arizona Cardinals in 2006. He got a late start on his rookie training camp after a contractual holdout then went 4-7 as a starter that season. He entered the 2007 season as the starter and went 3-2. But the Cardinals had veteran Kurt Warner behind him and turned the job over to Warner, who went on to great success. Warner led the Cardinals to the Super Bowl in 2009.

Leinart lost the Cards’ starting-job battle to Derek Anderson entering the 2010 season, and he was released. He spent the next two seasons as a backup to Matt Schaub with the Houston Texans. He spent the 2012 season as a backup to Carson Palmer with Oakland.