7:31pm: SI.com's Jon Heyman has confirmed that Rosenthal's report is indeed true. Acta will be let go, perhaps as soon as Monday.
5:17pm: Ben Goessling of The Washington Times spoke to team president Stan Kasten about Rosenthal's report. Kasten addressed the report but did not refute it, giving Acta the dreaded vote of confidence:
"We always support everyone here, and we always will. We're all in this together, trying to win everyday, trying to turn it around, and we're going to continue to try it. We know the future is bright, but we're not going to wait for the future to get here. We're going to do everything we can to speed it up. We've done that with kind of a frenetic movement of personnel pieces in the early part of the season. We're going to keep searching for the solution until we find it."
3:23pm: As a couple of commenters have pointed out, Acta is not actually the "youngest active manager in the majors." The Diamondbacks' A.J. Hinch is 35. Our readers are the best.
3:07pm: According to Ken Rosenthal of FOXSports.com, the Nationals are expected to fire manager Manny Acta as soon as Monday. Bench coach Jim Riggleman will replace him. As Rosenthal reports,
Acta, who at 40 is the youngest active manager in the majors, was hired by the Nats in November of 2006. He's gone 147-231 in two and a half seasons. The Nats have the league's worst record this season at 15-42.
Riggleman has managed for the Padres, Cubs and Mariners, and carries a 522-652 career managerial record. He worked as the interim skipper for the M's last season after John McLaren was dumped.