Nationals outfielder Bryce Harper is sticking with Under Armour for the foreseeable future.
The company announced Tuesday it has signed Harper, the reigning National League Most Valuable Player Award winner, to a multiyear endorsement extension. Terms of the deal were not disclosed, but ESPN reported the extension was believed to be for 10 years and would be the largest endorsement deal for a baseball player in history.
"I'm thrilled," Harper said. "Alongside Steph Curry, Cam Newton, Tom Brady -- MVP's -- and Jordan Spieth, it's such a great brand. Being able to be alongside those guys, it makes you want to play better and as best as you can, and do everything you can for the fans." 
Harper, 23, was the youngest unanimous MVP in history last season after hitting .330 with 42 home runs and leading the NL in runs scored, on-base percentage and slugging.
Harper initially signed with Under Armour in April 2011, 10 months after he was the No. 1 overall pick in the 2010 Draft.
Fellow high-profile baseball players Clayton Kershaw and Buster Posey also are endorsed by Under Armour, which also has reigning NBA MVP Curry, reigning NFL MVP Newton and current PGA Tour Player of the Year Spieth under contract.
"I try to go about it the right way. I want to try and get kids to play this game," Harper said. "I want to help them dream as they can. To get to the big league level. They can get here. … I will try everything I can to help this game succeed and put the Nationals out there. I just try to have fun and enjoy what I do."