For the final time in this baseball regular season, four presidential mascots emerged from behind the Nationals Park outfield fence on Wednesday afternoon and wobbled toward a finish line.

Bringing up the rear was Teddy Roosevelt, the lovable loser, Charlie Brown heading toward the football one last time.

But this has been a season of firsts for the Washington Nationals — first winning record, first playoff berth, first division title — and on the last day of the regular season, one more first was in store. So it was that the three leaders were felled by a green mascot meant to resemble the visiting Philadelphia Phillies’ Phanatic, leaving Teddy by himself as he trotted toward the tape.

“Another historic moment in a season full of them,” radio broadcaster Dave Jageler intoned as players gawked over the dugout railing and fans chanted Teddy’s name.

Team executives typically remain in character when discussing Roosevelt’s epic losing streak: “Teddy wrote history,” Chief Operating Officer Andy Feffer said after the game.

Okay, sure, Teddy winning the President’s Race is not exactly walking on the moon, but Neil Armstrong’s feat took far fewer tries.

But in truth, the streak was a contested issue, both inside and outside the team offices. Fans wondered if a Teddy win would kill the race’s charm, while team employees debated whether a Teddy win followed by a Nats loss would be seen as a bad omen.

Several players had long advocated for Teddy to win the fan-pleasing race, which is typically held in the fourth inning of every Nationals home game. Jayson Werth suggested the losing streak was emblematic of a losing culture, and on Wednesday Ryan Zimmerman expressed relief that the stunt had run its course.

“I am so glad Teddy won so we can stop talking about Teddy,” Zimmerman said after the game. “People get more excited for a mascot race than a game. Yes, I’m excited Teddy won. I’m ecstatic.”

Still, the groundwork for Wednesday’s result had actually been laid weeks ago. While there had been several false alarms in past seasons, the momentum this time seemed inescapable, especially after ESPN aired a long piece in mid-September narrated by Ken Burns and detailing Roosevelt’s many losses.

“I’ve been paying a lot of attention to the fact that one of the truly great presidents in history has never won a race,” Sen. John McCain deadpanned in the segment.

The next day, White House Press Secretary Jay Carney chimed in, telling reporters that the situation was “an outrage,” and adding, “I’m comfortable saying that my boss agrees with Senator McCain.”

After that, the floodgates opened. Teddy’s losing streak made the front page of the Wall Street Journal. A crew from “ABC World News Tonight” shadowed the mascot on Monday. The team fanned the flames by announcing the final three home games would be dubbed the “Teddy in 2012″ series, with daily Teddy-themed giveaways and video messages featuring Teddy with wrestler John Cena, Teddy training with the Army and Teddy huddling with McCain.

Just after 2 p.m., there was Roosevelt, ripping off his jersey to reveal a T-shirt blaring “Natitude” — the team’s 2012 slogan — as adults hugged and children jumped and screamed.

The mascot was outfitted with an Under Armour headband and gold Under Armour shoes on his big day, a fact not lost on sports marketing experts.

“It’s hard to build great marketing ideas outside your team, and they’ve clearly done so,” said David Schwab, an executive for the Octagon sports marketing agency who helps match brands with celebrities. “They maximized their opportunity. People have been talking about it for weeks. And they turned it into a publicity stunt while taking care of an existing sponsor at the same time.”

The concern that Teddy’s win would be a jinx disappeared almost immediately. Zimmerman, the team’s longest-tenured player, homered on the first at-bat after Teddy’s heroics, and Washington ran away with a 5-1 win over the rival Phillies.

“See what happens when Teddy wins?” joked Scott Ableman, a 48-year old Internet marketing executive and the creator of the Let Teddy Win Web site. “I’m looking for Teddy to go undefeated next season.”

In fact, Feffer and his staff are already working on concepts for 2013, with plans to make the race more interactive, adding social media components and at least one significant twist.

“We will definitely have another surprise,” he promised.

Many of the fans celebrating on Wednesday, though, were not worried about the marketing impact of Roosevelt’s win or the future of the race.

Those fans included 62-year old Seth Thievsky, who was wearing a Teddy sticker over a bandage on his chin covering a recent bicycle mishap. “Teddy is the Nationals,” Thievsky said. “He’s the symbol of the team; he and the Nats are one. He had to win today. It was poetic. It was mythic.”

They included Annette Lerner — wife of the team owner — who came to the game even though she was sick, on the promise of a Roosevelt win. They included. U.S. senators such as McCain and Charles E. Schumer, who sent out alerts on Twitter, where Teddy’s name became a worldwide trending topic.

They included Anna McDonald, whose 5-year-old daughter is such a big Teddy fan that she burst into tears the last time she saw him lose a race. And Michelle Morales, whose 4-year-old son Nico was promised by first baseman Adam LaRoche in August that Teddy would win this season. “Whoever came up with this is a genius,” Morales said as she surveyed Teddy merchandise.

And they included 8-year-old Margo Corsig, who played hooky on Wednesday just in case it was finally Teddy’s day.

“I thought it was awesome,” she said as she waited in line with her mom to buy a “Teddy in 2012” T-shirt. “I’ve been waiting for this win for a long time. I’m still gonna like him. Now I’m just going to be waiting for him to win twice.”

The Nats will open their home playoff schedule Wednesday against either the Braves or the Cardinals. Yes, there will be a fourth-inning presidents race. And the winner?

“It’s October,” Feffer said. “Anything can happen.”

Adam Kilgore and Amy Argetsinger contributed to this story.