On the Fourth of July at Robert F. Kennedy Memorial Stadium, hundreds of fans with furrowed foreheads turned away from the Washington Nationals ticket booths with puzzled expressions on their faces. They held up their hands, indicating with their fingers how many tickets they wanted to buy. "Need three" or "Need two," they yelled to the thousands of other luckier fans who headed into the old ballpark.

Several were asked what the problem was.

"Sold out," came the responses.

The crowd of 44,331, which came to welcome the first-place Nationals after their three-game sweep of the Cubs in Chicago, was the largest paid attendance of the season, surpassing Opening Day. Only scattered single tickets were available at odd spots around the park. Anybody who wanted more was out of luck.

Just past the midway point of the 162-game baseball season, the Nationals -- waiting to be sold to a permanent owner, playing in an antiquated stadium, fielding an under-funded roster of players -- have exceeded all expectations, and interest in the team has skyrocketed as well. Already 41,880 tickets have been sold for Thursday's 1 p.m. game against the Mets -- a time slot baseball calls a "businessperson's special" and regards as a tough sell.

By winning 26 of their past 32 games before yesterday's 5-2 loss to the New York Mets, the Nationals have a record of 50-32 after losing 95 games as the Montreal Expos a year ago. A team that drew 748,550 fans for its home games all of last season and ran a $10 million deficit has sold more than 1.3 million tickets, though yesterday, and is projecting a profit of at least $20 million.

On Independence Day, a crowd eager to see if the Nationals could keep it up was packed with every type of fan, from new converts to those who saw the last game in RFK in 1971 and have waited a third of a century for baseball's return.

U.S. Air Force Lt. Col. Ted McClesky, who has recently returned from Baghdad where he was training Iraqi military and police forces, brought his wife, Kim, and their two children, Claire, 11, and Steven, 7, down to the box seats before the game to get autographs from players such as Jamey Carroll, who ignored the summer heat to sign for hundreds of fans.

The newspaper "Star and Stripes is free in the combat area. I kept looking at the standings to find out how the Nats were doing and it was hard to believe," said McClesky, who returned to the United States about the same time the Nationals moved into first place.

"Now that he's home, hopefully forever, maybe the Nats will never lose," said Kim McClesky. As if on cue, the U.S. Air Force Singing Sergeants walked down the aisle past the McCleskys to prepare to sing the national anthem.

Nearby, Peter Eason and his 8-year-old son, P.J., were living out an old dream.

"I was here for the last [Senators] game in '71," said Eason, of Kensington. "After they left, it took me four years to go to an Orioles game. Now, I don't go to [Oriole Park at] Camden Yards anymore."

As summer has arrived, more and more families have brought children to games, swelling ticket sales to nearly 36,000 per game last week with the average paid attendance for this four-game series with the Mets expected to average more than 40,000.

"I used to walk to RFK, from 9th and S streets NW, to see the Senators," said 47-year-old Michael Smith, who had his 11-year-old son, Michael Jr., next to him.

"Everybody has taken to this team," added Smith, clad in red Nationals paraphernalia. "They play together, no matter what happens. They don't care who's injured. They just keep finding a way."

Several fans said they were surprised by the team's play, including its 41/2-game lead in the National League East Division that likely won't be overcome by next week's all-star break.

"The Nationals are probably 'over-performing,' but I love every game of it," said Randy Hinaman of Alexandria, who bought season tickets for his Capitol Hill lobbying firm and has already used the seats a dozen times himself.

Ironically, the big crowd on a holiday afternoon saw a sight that would have been unheard of in the last several decades of the Senators' time in Washington: Those teams never had to cope with the raised expectations of winning so many close games in such a short period of time. "You can't win every ballgame, even though it might seem like it," said Manager Frank Robinson, who then methodically outlined, especially for the benefit of new Nationals fans, the subtleties of managing for the long haul in a 162-game season.

"We haven't done anything yet if we don't finish," Robinson said. "We don't play for the glorified headlines. People don't look at how you start but how you finish.

"People have not looked at us as a contender. We don't care about what they think. We just take care of the business at hand."

Inside the Nationals clubhouse before the game, General Manager Jim Bowden expressed satisfaction with what has transpired thus far -- "This year, it's all worked" -- and quiet determination to maintain the magic through the second half of the season.

Bowden said that he feels empowered by Major League Baseball, which is expected to sell the team later this summer to one of nine prospective ownership groups, to make any personnel moves necessary to keep the team in contention.

"I can play to win," Bowden said. "We have the revenue. I've been told we have the resources to make the right move."

When the Expos arrived in Washington last fall from Montreal, who imagined that in their first season they would win so many games by close margins and have such a big division lead by July 4?

Phrases such as "single seats only" and "pennant race" were never expected to be heard at RFK Stadium this summer. But Washington's growing base of baseball fans had better get used to it.

"This is the birth of America's team," Bowden said. "Baseball is back in the capital city, baby."

Playing in front of a full house on Independence Day at RFK Stadium, catcher Gary Bennett gives chase to a foul ball. Washington fell to the Mets, 5-2.