Washington Nationals Manager Jim Riggleman called General Manager Mike Rizzo 45 minutes before Thursday afternoon’s game and asked for a meeting. Minutes later, Riggleman told his boss that he wasn’t getting on the team bus after the game unless Rizzo agreed to have a meeting with him in Chicago to discuss picking up his contract option to manage in 2012.

Riggleman says he just “wanted to have a conversation in Chicago” on the subject. Rizzo says it was an ultimatum. It’s a distinction without any difference whatsoever. The only words that mattered are, “I’m not going to Chicago unless . . .

Not getting on the bus? Not getting on the plane? Talk turkey or I quit? In three hours? Try that with your boss. Give me $700,000 for next year or I’ll resign in the middle of a long winning streak and say I didn’t get proper respect and fair treatment.

Riggleman has a decent case for continuing as manager, but not a compelling one. His team has a 38-37 record and has won 11 of 12. But just a month ago, the club returned from a 1-7 road trip in such disarray that Rizzo cut short a scouting trip to come back to D.C. to “put out fires” in the clubhouse.

Since at least February, Riggleman has been working himself up, getting more frustrated. If you haven’t heard his dissertation on this subject, never for attribution, then you haven’t talked with him. I’ve taken the position that picking up his option for next season was a low-cost and decent move — not absolutely necessary, but the better course.

In the last month, Riggleman has almost certainly read tea leaves that made him feel Rizzo had lost confidence in him as the Nats’ long-term manager. So, he left with an chest-out exit that said: “A man’s got to do what a man’s . . .

Yet he disdained an obvious alternative, one that, with a run of luck, might have brought him a very happy ending. Why not try to take a Washington baseball team to a winning record for the second time since 1953? Or come close. Then, no team on Earth could, or would want to, deny him a new contract. In ’12, he probably would have Stephen Strasburg and Adam LaRoche back from injury as well as, perhaps, more free agents. Rig says he’s never had the horses. If he did, he’d show ’em. Now, just as he might actually have gotten ’em, even if granted grudgingly, he probably ended his managerial career.

In Rizzo, Riggleman couldn’t have found a worse boss to nag about a new deal or one who would respond worse to his lobbying in the media (me included) for help.

Why? Because Rizzo faced the same obstacles when he became GM. Instead of whining about a longer deal, he did such a strong job that the Nats did what was obvious: They gave him a five-year contract. Rizzo replaced Jim Bowden on an interim basis in 2009. Then, the next year, he was on a short leash like Riggleman this year.

Rizzo said ex-president “Stan Kasten told me, ‘Forget the [expletive] contract. Own the job. Just be the [expletive] GM. Prove you’re the guy.’ ”

And Rizzo, even though he’d spent his whole life working up the baseball chain to be a GM, swallowed and did it. Talk about playing the wrong card with the wrong guy.

The Riggleman resignation bombshell knocked the Nats’ clubhouse sideways.

“In the locker room, I wondered, ‘What are they doing in there behind closed doors? Are they going to announce Jim’s extension,’ ” said John McLaren, the bench coach who will serve as Riggleman’s short-term replacement. “Then when everybody came out, I wondered if somebody died.”

A job was dead anyway. Ironically, Riggleman’s chances for ’12 were probably better six weeks ago. Then came the Marquis moment. In Baltimore, pitcher Jason Marquis, after being taken out of a game, cursed Riggleman from behind the dugout for what the manager estimated was an inning and a half.

After the game, Riggleman, 58, followed Marquis, 32, around the clubhouse and gave him the full-blue here-I-am-if-you-want-a-piece-of-me. Riggleman was so furious that he went back in his office and then came back to chew out Marquis again. Both times, the betting would probably have been on the fitness buff Riggleman. Asked if the details were correct, Livan Hernandez said, “That’s baseball.” And it is — just baseball.

The blowup did Riggleman’s sense of dignity good. But the team instantly slumped, and enough players were on the phone to Rizzo that he hustled back from a scouting trip to D.C. to “have more meetings than Congress” to “put out fires,” including an intense meeting with Riggleman.

Again, Riggleman told Rizzo he needed a longer deal to do his job properly and that any manager in whom a team had confidence would have a better contract. Rizzo asked what an extra year would change: Command authority; don’t demand it by contract.

Riggleman, at Rizzo’s insistence, called a get-on-the-same-page team meeting. Suddenly, as happens often in baseball, the cold team got hot. The Nats won two out of three from the Phillies, then went 6-5 on a West Coast swing. Back home, they completed a beauty of an 8-1 homestand with a 1-0 victory on Thursday to sweep Seattle.

Then they came back in their clubhouse and learned their manager had resigned because he didn’t like his contract.

“I was always taught that one of the cardinal rules of baseball was that no individual can put his interests before those of the team,” Rizzo said.

When spring training started, the Nats didn’t know who their long-term manager would be. It might be Riggleman, if he could make a bigger impression than he ever had in his various stops. But if he didn’t max out his chance, they’d get somebody else.

“Jim is a great handler of a game,” one Nats source said. “But you can get seven fans that can ‘handle a game.’ It’s what happens after you come down the dugout steps after a game that really matters. That’s when you find out who’s a big league manager. That’s when Jim goes in his office. He thinks his day is over.”

Riggleman thinks he did a fine job. What do they want? What do I have to prove?

“I know I’m not Casey Stengel, but I know what I’m doing,” he said Thursday. “If I’m not the person you want to go down the road with, let me know.”

He wasn’t that person. But if he’d won enough games, he might have been. Rizzo wasn’t in any hurry to extend Riggleman. But Rizzo wasn’t in a rush to fire him either.

The GM felt he had proved himself the hard way. Why shouldn’t Riggleman, with the worst record in baseball history of any 12-year manager, have to do the same?

Riggleman leaves absolutely convinced he was done wrong. Rizzo is now just as convinced that, on his last day of work, Riggleman proved he wasn’t the man for the job.