Last month, D.C. Mayor Anthony A. Williams called Major League Baseball's bluff. Now, we're finally going to see what cards everybody is holding in the game of relocation poker.

The Mayor promised that the District would build a 41,000-seat ballpark for the Expos, constructed entirely with public money, if they would move here from Montreal. The cost of the park, depending on the site, might be as high as $383 million.

Williams's new proposal, if it came to pass, would increase the value of the District's previous contribution to a new park by almost $100 million over last year's offer. Suddenly, the staggering amount of cash heading from Washington hands toward baseball in a relocation of the eyesore Expos could approach $600 million.

To illustrate the dimensions of this windfall, the Washington Baseball Club, headed by financier Fred Malek, could probably now afford to offer a purchase price of $200 million for the Expos, since it does not have to contribute to building its new park. Any competing group seeking the team would certainly have to pay as much. Baseball owners are good at addition. The cost of a new District ballpark, plus the likely Expos purchase price, now appear to be in the $550 million to $600 million range.

Feel free to smack your forehead. All this to win the woebegone Expos?

Who gets to divide up these suddenly richer spoils? Why baseball's 29 owners, since the sport itself owns the Expos. And what would such a gaudy price tag for the Expos do to the value of other franchises? There's an excellent chance it would add equity value to every team in the sport, just as a high sale price for the house down the street tends to increase the value of every house on the block.

No wonder the game's been buzzing since Williams made his May presentation to baseball brass. Flash: Money talks again.

"The reaction was apocalyptic," said one high-ranking baseball official yesterday. "That proposal got everyone's attention."

Williams's gaudy promise to baseball -- which is far from the same thing as a signed, sealed and delivered deal -- has now forced the sport, once and for all, to decide whether it will put a team in Washington over the objections of the Orioles.

"This is a seismic shift," said Malek yesterday. "The mayor has put us in the best possible position to get a team. And we were not in the best position before."

The District, even with Williams's current promises on the table, has plenty of Expos hurdles, perhaps insurmountable ones. However, Northern Virginia, which claims that it can fully fund a new ballpark near Dulles International Airport, has even more problems. Dulles Airport? Right now, the District is at the center of baseball's focus. Northern Virginia has moved out toward the edges.

At the moment, no one knows whether Williams's promise, even if he can deliver it, will be enough to sway Commissioner Bud Selig or persuade three-quarters of all owners to vote against one of their own. Selig has genuine and justified concerns about moving a team within 40 miles of the Orioles. Only the disingenuous would claim that Orioles attendance would be identical with the Expos here. Peter Angelos, like any owner, will protect his interests, lobbying his fellow owners with all his might.

But one thing is now certain. The District will never surpass, or perhaps even approach, what Williams claims he can produce if baseball gives the nod. The mayor has made the ultimate, some will say extravagant, offer-you-can't-refuse bid to get the Expos.

"We're going to get the answer to the Washington question now," said another baseball executive close to the relocation decision. "If we don't take this [offer], we wouldn't have the gall to come back and ask again. And we have a lot of gall."

Look at what the District is offering and catch your breath. For a dilapidated franchise that some think should be contracted out of existence, the fifth-largest market in the country is offering to build a ballpark worth at least $350 million and pay a fancy $200 million price tag. According to sources, the mayor's financing plan would only cost local Expos owners about $40 million worth of lease obligations. And they'd get to keep all parking, concession and suite revenues. With such a deal, a Washington team could be one of those "jewels" the game raves about. Will baseball owners have the wits to say, "Thanks! We accept. Sorry, Peter."

If there was ever a last, best and final offer, the District has just made it. At last, closure may be approaching.

Can Angelos, if he has Selig at his side, keep baseball from offering the District a shot at the Expos? The odds are probably even. But if Williams's concept isn't enough, then the District should tell baseball never to bother darkening its door again.

If baseball does decide to give the District the first shot at the Expos, it will, according to insiders, come in the form of a contingency arrangement. The relocation committee now realizes that no Washington politician can deliver a deal involving passage of new laws and bond issues on pure speculation that baseball may, or may not, let the Expos come here.

So, in true cloak-and-dagger baseball fashion, the District would probably be given -- with full baseball "deniability" -- a time window to get its deal finalized and legalized in every detail. Mid-September is a decent guess at a drop-dead date.

If baseball actually deigns to kiss the District after all these decades, it is no sure thing that the District will be in the mood to give baseball a hug in return.

Getting the whole town on board for such an expensive ballpark project will be, at the least, a battle royal. If we ever reach that decision point, let all sides makes their cases. At such prices, it's far from an obvious choice. In recent days, voices have already been raised saying, "Not on this site" or "not at that price."

No matter what the outcome, Williams and his supporters on the city council have finally given the city the best shot it will ever get at another major league team.

If baseball doesn't offer us a shot at the Expos on the terms that are now on the table, then it never will. Case closed.

If baseball does give Williams a chance to push his ballpark proposal, then the city will either beat him or back him.

Either way, we have an answer. The District will choose -- what a nice word -- not to take the Expos at such prices. Or, after a third of a century, Washington will finally get a baseball team.