It looks like a five-month poker game between players with equal stacks of chips. Federal regulators are coolly threatening to block the planned $83.9 billion Exxon-Mobil merger if the parties don't shed more than 1,500 service stations.

Nobody believes that lawyers for the Federal Trade Commission are bluffing, but the highly public stare-down obscures the jitters behind the bravado. With the pace of acquisitions and joint ventures soaring, antitrust enforcers are strapped for money and manpower as never before, according to government officials and experts.

Mega-mergers are draining resources from the review of smaller deals that a few years ago might have set off alarms and been scrutinized with greater care, specialists say. And some non-merger activity, such as price fixing and bullying tactics by dominant firms, is passing by unnoticed. The nation's trust busters are simply overwhelmed, and Corporate America is catching on.

"We'll get executives asking, 'How do you think x or y transaction would fly?' " said Robert Skitol, a partner at D.C.'s Drinker, Biddle & Reath and a former FTC staffer. "I tell them that on the face of it, that's a very problematic idea. But then I say that in all honesty when you look at mergers that are getting through these days, nothing is unthinkable."

Since the start of the Clinton administration, regulators have taken a more activist approach to antitrust, talking tough and signaling to market-leading firms that mergers that could raise prices will be challenged. Those aren't empty threats. In the past two years government lawyers have prevailed in litigation against drug wholesalers, Toys R Us Inc., Staples Inc. and Office Depot Inc. A resolution in the Justice Department's case against Microsoft Corp. is expected soon.

But a monsoon of mergers and joint ventures has swamped the agencies and far outpaced increases in federal funding. For consumers, that could mean higher prices for dozens of items, from groceries to hospital care. The FTC and Justice Department are considered lead players in the government's anti-inflation efforts, policing corporations seeking to swallow or muscle out competitors and charge more for products and services.

Since 1991, the number of proposed deals filed with both agencies has more than tripled, to 4,679, but staffing levels over those same years have barely budged. The FTC's Bureau of Competition, for instance, employs just five more people than it did in 1991, even though those staffers are now supposed to study hundreds more filings. The Justice Department's antitrust division employed more people in 1980 than it does now, although deals today are vastly larger, more complicated and more time consuming.

The shortfall puts leaders of these two agencies in a pickle. On the one hand they desperately need reinforcements. At the same time, they don't want to send the message that they're too understaffed to handle the onslaught, which might lead companies to conclude the government is merely posturing when it threatens to sue. Nonetheless, both the Justice Department and the FTC have beseeched Congress for additional bodies, pronto.

"We're terribly squeezed," FTC Chairman Robert Pitofsky said. "We're being asked to do much more because of the merger wave. While our resources have been augmented somewhat, the increase is nowhere near enough for all the merger review and non-merger work we need to do."

This week Congress unveiled fiscal 2000 appropriation figures for both the Justice Department and the FTC, giving each a modest raise. But the funding levels have yet to recover from the Reagan administration, which considered antitrust enforcement a meddlesome intrusion and slashed about half of both agencies' budgets from 1981 to 1988.

Enforcers have since learned to do more with less, but they also are cutting back the rate at which they challenge deals. In the past eight years, the percentage of filings that are investigated by the agencies has held steady at about 2 percent. But what happens next? In 1990, the FTC forced corporations to drop or change their proposals 35 times. Last year, the agency forced changes to just 30 proposed deals--although 1,800 more deals were reviewed.

Government lawyers believe that mergers, particularly the huge ones, are getting sufficient attention, and indeed dozens are studying the merger proposal of Exxon Corp. and Mobil Corp. The worry is that hard-to-spot wrongdoing, like market allocating, is going unnoticed because resources have been steered away from those areas. Companies, after all, are required to alert the government about mergers but "people don't come to us and say 'We're price fixing,' " noted Michael Antalics, the FTC's assistant director for mergers. "Those are the type of cases you have to go and look for."

Erring on the side of discretion, private attorneys won't cite transactions that should have been blocked or changed, because the government can retroactively undo a deal. Nonetheless, these attorneys have quietly informed top agency bureaucrats that envelope-pushing transactions are starting to slip through the net. In other instances, companies are dragging their feet when it comes to divesting assets, as required by consent decrees.

"Staffers are so busy looking at the next deal there just isn't time to check on the last one," said George Cary, antitrust lawyer at Cleary, Gottlieb, Steen & Hamilton.

Cary added that slimming down antitrust enforcement has had some positive effects. Government lawyers can't afford to dawdle these days, which means quicker decisions and less agonizing limbo for corporations. And he pointed out there there are still hundreds of plaintiffs lawyers filing antitrust actions, drawn by the prospect of triple damages and providing the public with what amounts to an army of privately funded attorneys general.

Still, the resource crunch is starting to undermine the government's standing in negotiations. "The Exxon deal is coming up any day now. If they choose to litigate, there's probably nothing else the FTC will be able to do," said Albert Foer of the American Antitrust Institute, a nonprofit. "So to some extent, the conclusion is preordained."

CAPTION: The FTC's Robert Pitofsky said his agency is "being asked to do much more because of the merger wave."