WASHINGTON - Our Park. The Series.

That was the only message being advertised Wednesday as the Washington Nationals took batting practice in their home ballpark along the Anacostia River.

The plea for ticket sales, visible on every last bit of electronic advertising space in Nationals Park, had nothing to do with the Arizona Diamondbacks, the team Washington was playing in a three-game series that concluded Thursday night. It was all about the long-awaited weekend series against the Phillies - the team whose fans have piled into buses and invaded the nation's capital in recent years.

Andy Feffer, the chief operating officer for the Nationals, made the matter personal over the winter when he announced that tickets for the three-game series with the Phillies that begins Friday would initially only be made available to Washington season-ticket holders and residents of Maryland, Virginia and the District of Columbia.

"We've heard it enough, we've seen it enough, and I don't like it any more than anyone else," Feffer told the Washington Post in early February. "We're trying to build a team here and nothing irks me personally or the people here more than to see another team's fans - particularly Philly fans - in our ballpark holding up signs. That's not the way it should be. And I think we've got an opportunity here to do something different."

Exactly how well Feffer's "Take Back the Park" initiative worked is unknown. After his chatty winter about the issue of Phillies fans invading D.C., the Nationals executive declined to be interviewed by the Inquirer for this story.

We do know that tickets are still available for all three games between the Phillies and the first-place Nationals, a team brimming with young talent, including Friday night's starting pitcher, Stephen Strasburg, and 19-year-old centerfielder Bryce Harper, who made his major-league debut Saturday in Los Angeles. Harper was hitting third for the Nats Thursday night.

Harper still has a boy's face, but it is attached to the perfect baseball body, allowing the teenager to whip his bat through the strike zone with intimidating swiftness and force. In just his second home game Wednesday, Harper had three hits, including a ninth-inning double that allowed him to score ahead of Ian Desmond's walk-off two-run home run.

A crowd of 16,274 was in attendance to see the Nationals end a five-game losing streak against the Dimaondbacks Wednesday. The night before, when Harper made his home debut, a crowd of 22,675 was on hand, which meant there were more empty seats than people.

Since moving to Nationals Park in 2008, the team has drawn more than 2 million fans just once and ranked 13th or lower in National League attendance every season. They have drawn 35,000 or more fans to a game just 23 times in the last three seasons and six of those games involved the Phillies, so you would think they'd welcome those busloads of fans making the trip down I-95.

It will be interesting to see how many Phillies fans make their way into the Nationals' home park this weekend, but Nationals general manager Mike Rizzo realizes that Feffer's artificial initiative will not be the determining factor about the future health of the franchise.

"I've always said that Philadelphia has earned the fan base that they have," Rizzo said. "They have a terrific fan base, a terrific organization, a terrific ballclub. They are the king of the mountain.

"My 'Take Back the Park' plan is proving that we can beat [the Phillies] to the point where [their fans] don't want to come [here] anymore and our fans are going to fill the park."

When the failing Montreal Expos moved to Washington in 2005, there was skepticism about whether baseball could make it in the land of politicians. Two incarnations of the Washington Senators failed here - the first one becoming the Minnesota Twins in 1961 and the second one becoming the Texas Rangers in 1972.

In fairness to the Washingtonians, they were forced to watch a lot of bad baseball over the years. Before moving to Texas, the Senators had one winning season in 11 years and lost 92 or more games eight times. Before moving to Minnesota, the Senators played above .500 just one time in the previous 15 seasons.

"I guarantee baseball can make it in D.C.," Rizzo said. "You have to put a winning product on the field. We have ourselves an energized, exciting and athletic group of players out here and this place is buzzing on a lot of nights and it's only going to get better. It's going to be the big ticket and it's going to be a tough ticket to get in this town."

A small survey of fans at Nationals Park on Wednesday night offered some insight into the challenges of putting together a successful baseball franchise here.

"We didn't have a team here for 30 years and when the Senators left, I lost all interest in baseball," said Jeff Burcham, a 63-year-old financial planner who was born and raised in D.C. "I couldn't embrace the Orioles. It was nice to have a team come back to Washington.

"If we start winning like [the Phillies] did . . . you guys were the example. You guys sell your park out every night. That's what happens if you win."

Many fans did embrace the Baltimore Orioles after the second departure of the Senators and they remain loyal to the American League team even today. Baltimore's Camden Yards is a far more picturesque ballpark - unless you enjoy the obstructed view of the Capitol beyond the left field wall at Nationals Park. Baltimore's Inner Harbor is also a more inviting area than the area the Nationals constructed their ballpark.

The Orioles, of course, have had their own share of recent attendance problems, thanks to 14 straight losing seasons.

"I feel like I can claim the Nationals because all the people who grew up here like the Orioles," said Michael Gerber, a 31-year-old mental-health research evaluator who moved to Arlington, Va. from New Orleans three years ago. "I feel like, as a transplant, I'm a real Nationals fan."

Gerber's friend, Aaron Rosenthal, admitted he is torn between the teams, although he arrived at the ballpark wearing a Harperstown T-shirt he purchased when Harper made his professional debut last summer with Washington's minor-league affiliate in Hagerstown, Md.

"I love Camden Yards," said Rosenthal, a 30-year-old government worker. "It's a great place and I love the American League. The N.L. has been hard to get used to."

Kenny Dixon, 34, is a Marine from Georgia stationed in Quantico, Va. A season-ticket holder, he attended Wednesday's game with his wife and three kids and admitted he is an Atlanta Braves fan who also loves the Nationals.

He does not enjoy the annual invasion of Phillies fans.

"When the Phillies come into town, [their fans] sit out there and drink all day and they are just a bunch of idiots," Dixon said. "Honestly, if I was in Philadelphia to watch a game, I'd wear a Phillies T-shirt and go to the game and watch it because . . . when in Rome.

"It's a baseball game. It's not a life choice."

As distasteful as he finds Phillies fans, Dixon does not mind selling them tickets to Nationals Park through the StubHub web site.

"I can make money off them," he said. "If Phillies fans are going to come down here and pay three times what I paid for my tickets, then come to the game and I'll sit at home. It doesn't bother me one bit.

"A game like [Wednesday's against Arizona], if I was to sell my tickets, I might be lucky to get eight bucks a pop for them on StubHub. When the Phillies come to town, I'll sell them for 60 bucks apiece."

Contact Bob Brookover at bbrookover@phillynews.com or @brookob on Twitter.