Randy Johnson's bid to become the 24th pitcher to win 300 games has been postponed.

Wednesday night's game between the San Francisco Giants and Washington Nationals was called off because of an unplayable field. Thunderstorms delayed the 7:05 p.m. start time, and Nationals Park was drenched by the time the rain started to subside around 10:45 p.m.

The game will be made up as part of a doubleheader Thursday starting at 4:35 p.m. Johnson is scheduled to pitch the first game for the Giants.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

WASHINGTON (AP) _ The Big Unit had to wait on Mother Nature, even with history on the line.

Randy Johnson's bid to become the 24th pitcher to win 300 games was delayed Wednesday night by a series of thunderstorms so severe that even the Capitol dome couldn't be seen from the upper deck of Nationals Park.

The game between Johnson's San Francisco Giants and the Washington Nationals was scheduled to start at 7:05 p.m., but the tarp went on the field before batting practice. It was removed during a break in the storms around 8 p.m., but it was soon put back on when weather radar accurately predicted the imminent arrival of another line of storms.

Officials said they expected the rain to end by about 10:15 p.m., and they planned to start the game afterward _ assuming the field could be made playable.

"We are going to play this game," Nationals president Stan Kasten said as the clock hit 10 p.m.

Kasten said he and Giants president Larry Baer, also in attendance, were determined to wait out the storm "because of the significance of this game." Kasten also said the weather forecast for Thursday afternoon was not promising, making him wary of trying to make up the game as part of a day-night doubleheader. The series wraps up Thursday, and the Giants are not scheduled to visit Washington again this season.

"We have a series of tough choices," Kasten said.

Before the storms hit, Giants manager Bruce Bochy was asked how Johnson might handle a rain delay.

"That's where we're going to rely on Randy," Bochy said. "That's what he's good at. He knows his body. We're going to rely on him. He's smart about being honest."

Johnson was aiming to get win No. 300 on his first attempt. He got his 299th victory last week when the Giants beat the Braves 6-3.

Afternoon discussions also centered on whether the 45-year-old lefty will be the last to reach the milestone. Pitch counts, quick hooks and an overall abundance of caution with pitchers have made consistent big-win seasons a rarity.

"He's going after a tremendous accomplishment that probably we'll never see again," Washington manager Manny Acta said. "It's becoming tougher and tougher."

Only four pitchers have averaged at least 15 wins over the last six full seasons, and the career leader among those four _ Roy Halladay _ has only 140 wins at age 32, putting him about a decade away from 300 at his present pace. The only contenders above 200 wins are 46-year-old Jamie Moyer (250), 36-year-old Andy Pettitte (220), 37-year-old Pedro Martinez (214) and 42-year-old John Smoltz (210).

"I think we'll see it again. It'll be a while," Bochy said. "Of course, there's Moyer. He can pitch until he's 50, I guess. The way bullpens have evolved in baseball, it makes it more difficult for these starters to get the decisions. They're not in there when the game's decided. Randy, if you look at his decisions, and the guys who have won 300, that's one common denominator that they have. That's why it's going to be a lot more difficult."