WASHINGTON — With six games left in the season, the skidding Braves are on the precipice of dubious distinction, with the possibility of owning one of the worst collapses in baseball history unless they get their act together.

Their wild-card lead over St. Louis was cut from 8 1/2 games Sept. 5 to two games by the surging Cardinals, who blew a late lead and lost 8-6 to the New York Mets on Thursday. The Braves’ magic number to clinch the wild card is five.

“We need to come out and start winning games, whatever it takes,” catcher Brian McCann said after losing 4-0 at Florida on Wednesday, the Braves’ third loss in four games and 15th in 24.

After losing consecutive series against the Mets and Marlins, two teams long since eliminated from playoff contention, the Braves had a day off in Washington before a three-game series against the Nationals starts tonight.

Third baseman Chipper Jones said the Braves, who lately have struggled to score runs or to prevent runs, have left themselves no wiggle room and must go all out the rest of the way.

“We’ve still got everybody in the rearview mirror,” he said. “We’ve just got to go take care of business. We’ve got to get some good pitching performances, and we’ve got to start hitting with some guys on base.”

He was the asked whether the Braves were in the right frame of mind to stem their ongoing tide.

“I think so,” he said. “We’re only as good as tomorrow’s pitcher. If we get a good pitching performance, I think we’ll win ballgames. If we don’t, we struggle coming from behind. But I’m still optimistic that this club’s got enough in the tank to get it done.”

If they don’t soon, it could be too late. The Cardinals went 12-2 with a 2.48 ERA in their previous 14 games before Thursday, and they’ll finish with series against the lowly Chicago Cubs (in St. Louis) and the Houston Astros, who already have surpassed 100 losses.

The Braves face the Nationals, who were 9-2 with a 2.08 ERA in their past 11 before Thursday, then close the season with three against National League East champion Philadelphia.

The weekend series in Washington has suddenly become the most important of the season for the Braves, who are 8-7 against the Nationals, including 3-3 at Nationals Park.

“Maybe it’s good to have a day off now, regroup and get ready for the next six games,” said Braves manager Fredi Gonzalez, who was asked if he still thought his team would be better for having gone through such a bad stretch, as he had said recently.

“When we survive it, yes,” he said Wednesday. “You come out of these tough, and I think you become a better club when you get through it.”

If they get through it.

“We’ll enjoy [Thursday’s off day], then try to regroup,” said Braves pitcher Derek Lowe, who worked 6 1/3 innings Wednesday in losing his fourth consecutive start, remarkably the second time in 23 starts that a Braves pitcher lasted more than six innings.

That explains why the bullpen has shown signs of fatigue, the last of the team’s pillars to crack. Only Pittsburgh’s relievers have worked more innings than Atlanta’s.

The Braves have used four or more pitchers in 34 of 45 games since Aug. 3. In that same span, the Phillies have used four or more pitchers in 18 of 46 games, with four of those incidents coming in the past week after they clinched a playoff berth.

“We made it definitely kind of tough on ourselves,” Lowe said of the shrinking wild-card lead. “But you’re still going to have a lead going into [tonight]. If we keep winning, we’re going to make it.”

Keep winning? The Braves must get back to winning, not keep winning.

They went 40-20 with a 3.49 ERA and 4.5-run scoring average from June 19 to Aug. 25. Since then, the Braves are 9-15 with a 4.34 ERA and 3.25-run scoring average.

They are 4-8 in their past 12, including 1-4 in one-run games. The Braves scored three runs or fewer in six of those 12 games.

The Cardinals were 5-1 in one-run games during their 12-2 tear before Thursday.

No team has blown a nine-game lead in September to miss the playoffs. The Boston Red Sox, struggling as mightily as the Braves, could become the first to do that after seeing their nine-game lead shrink to 2 1/2 before Thursday. The Braves last led by nine games Aug. 29.

In the wild-card era, no team has led by as many as 8 1/2 games on Sept. 5 — as the Braves did — and failed to win the wild card.

Atlanta and Boston are trying to avoid joining these teams in the ignominy of epic collapses of the past 50 years.

  • The 2007 Mets blew a seven-game lead over Philadelphia with 17 games left. The Mets fell so hard and swiftly that they finished two games behind the Phillies.
  • The 1995 Angels led Texas by 9 1/2 games and Seattle by 12 1/2 with 37 games left. The Angels went 12-26 with a 5.64 ERA to close the season, then lost to the Mariners in a tiebreaker.
  • The 1964 Phillies had a 6 1/2-game lead over Cincinnati and St. Louis on Sept. 20 with 12 games left. The mayor and 2,000 fans greeted the Phillies in their return from a road trip. Then Philly had a 10-game losing streak. The Reds won nine in a row, and the Cards won eight in a row, each team sweeping the Phillies. St. Louis won the pennant.
  • The 2009 Tigers blew a seven-game lead over Minnesota with 26 to play. Detroit still led by three with four games to play, but blew it.