But later Friday, Rizzo said an official announcement regarding Riggleman's future might not come for some time.
Last offseason, Riggleman signed a two-year deal, but only 2010 was guaranteed. The team could buy him out after this season.
Washington is 42-55 but on pace to improve from last season, when it went 59-103. It was Riggleman who brought accountability back into the Nationals' clubhouse for the first time since Frank Robinson managed the club from 2002-06.
"Yes, he will be back next season. He has done a terrific job," Rizzo said before Friday's game. "We have a great relationship. He is a baseball rat. I can't beat him to the ballpark. One of these days, I'm going to beat him to the ballpark. He runs at 8:00 a.m. and he is at the ballpark by 11.
"He is a terrific baseball manager. He has great respect from his peers in this game. When the game starts, he is as good as anybody in the game. He has the respect in the clubhouse. He is a diligent worker and he is a loyal employee."
Said first baseman Adam Dunn, "I think Jim deserves it. ... He definitely deserves the opportunity to manage the club when it's healthy."
Riggleman replaced Manny Acta as manager of the Nationals after the All-Star break last season. The club went 33-42 and finished the year on a seven-game winning streak.
"I love managing, period. This is what I want to do," Riggleman said. "If I get the opportunity to manage the Nationals and if it's my last job in baseball, that would be a real thrill for me. You know, we have a lot of season to play, so hopefully, I'll be worthy of coming back. That's going to depend on a lot of things -- a lot of people's thoughts and all that. I have really enjoyed it. I like working for Mike. So I hope it happens. I'm going to cherish every game in the meantime."
This is Riggleman's fourth managerial stint, after leading the Padres, Cubs and Mariners. His best season as a skipper was in 1998, when he guided the Cubs to the playoffs after they won a National League Wild Card tiebreaker over the Giants. The team lost to the Braves in the NL Division Series, 3-0.