Addressing the March 8 presidential cataclysm known as "Super Tuesday," Robert Herbst positively rings with alarm.

"Today we're at DEFCON 3," he said Thursday, using Pentagon terms for a "defense condition" of increased readiness. "In a day or so we'll be at DEFCON 2. Probably by next week we'll hit DEFCON 1."

For Herbst of Blair Television -- one of a dozen "rep firms" doing business with the eight Super Tuesday contenders on behalf of some 600 local stations in about 150 media markets across the South and elsewhere -- "DEFCON 1" is the political equivalent of a nuclear exchange.

So, too, for the candidates' media strategists, who are busy deploying 30- and 60-second television and radio commercials over a primary election battlefield of unprecedented size and wattage. Their strategies will be put to the ultimate test on a single day, when four Republican presidential candidates vie for 803 delegates in 17 states, and four Democrats compete for 1,307 delegates in 20 states and one U.S. territory.

"It is a huge and complex task," said Anthony M. Fabrizio, media buyer for Sen. Robert J. Dole (R-Kan.). "And anybody who wasn't prepared for it months ago is going to be overwhelmed. Could you imagine sitting there, the day after New Hampshire, with 21 days till Super Tuesday . . . and you hadn't even looked at it? These things just don't happen overnight."

"It's a question of maximizing your money," said Harriet Yellin, media buyer for Massachusetts Gov. Michael S. Dukakis (D). "It's never going to be what you want it to be, unless you're a Republican. So you're trying to think about every market individually, what it means to your campaign and what its requirements are."

Because a campaign conceivably could spend as much as $10 million advertising for Super Tuesday, all the candidates will depend heavily on coverage from local and network news.

While the best financed, such as Vice President Bush, may use as much as $3 million -- the minimum necessary, according to several experts, to make effective commercial buys across the South -- the other contenders must carefully target their resources, buying only in areas where they are well organized and believe their most likely supporters to be.

And they will commit the bulk of their resources to the final few days.

"You don't have enough time to try and win over your opposition," said Robin Roberts, media buyer for Rep. Jack Kemp (R-N.Y.), whose Super Tuesday media future turns on his performance in the March 5 South Carolina primary. "You have to find your supporters, and maybe some leaners, and get them out. If you're going duck hunting, you've got to go where the ducks are."

That is even truer for the cash-strained Democrats: Rep. Richard A. Gephardt of Missouri, Sen. Albert Gore Jr. of Tennessee and Jesse L. Jackson. Jackson's campaign manager, Gerald Austin, said he expects to buy television time only for the final four days. "Basically our strategy is a free-media strategy," Austin said. "We have a hard-working candidate and a DC9, so we'll be hitting three or four markets every day."

"If the amount spent by any of the Democrats exceeds a million dollars, I'll be very surprised," said Robert Beckel, who, as former vice president Walter F. Mondale's campaign manager, spent about half that on just three southern state primaries in one day in 1984. "This is a delegate game, so you can bet they'll be buying congressional district by congressional district, and not full-state buys or full-region buys."

Deciding where to buy involves such interlocking parts as rating points, demographic information and each campaign's own polling data as well as the larger political realities.

The Democrats likely will avoid major markets in the home and neighboring states of their rivals -- Massachusetts, Missouri, Rhode Island and Tennessee -- and the Republicans will use resources in similar fashion. "Gore has got the toughest call of all," Beckel said. "He's got the greatest expectations and the most places to defend."

"If I were Al Gore, I'd certainly want to tie down my base, win Tennessee and work Kentucky pretty hard," said David Axelrod, media consultant to Sen. Paul Simon (D-Ill.), who last week chose not to compete on Super Tuesday. "But he has to have a pan-South strategy."

As for Gephardt, Axelrod said, "he's got to play in Florida and Texas, and there's real market potential for his message in Alabama and maybe Arkansas . . . . One thing he's playing for is not just delegates. You want to have a few states light up for you on that tote board."

"If you're Bush, you go right across the South," Beckel said. "If you're Dukakis, you buy Atlanta, Miami and Raleigh-Durham. Dole buys Missouri, Oklahoma and North Carolina, Texas, where he has some potential, Maryland and probably a little of Virginia." Republican Pat Roberston, meanwhile, can be expected to buy the Bible Belt, particularly in Mississippi and Louisiana to reinforce his born-again base.

Preliminary television buys of both parties' contenders tend to confirm these perceptions.

About 85 percent of the typical campaign's media budget will go to broadcast television stations -- mainly network affiliates -- with the rest allocated to reach the segmented audiences of radio (10 percent) and cable television (5 percent).

Beyond the question of where to buy, the candidates must decide what to buy. While everone will put their spots in the network morning shows and near the local news, Republicans may use such shows as "Murder She Wrote," "L.A. Law" or "20/20," which tend to attract older, more politically active viewers. Democrats likely will buy those programs, too, and situation comedies such as "Growing Pains," which tend to attract younger viewers.

The keys are what the television industry calls "reach" and "frequency." A rule of thumb is that for a commercial to be effective, every viewer in the market (that is, "reach") must see it at least five times ("frequency").

One problem all the candidates could face is the need to change ads on short notice, to respond to a negative ad from a rival. "If an opponent comes out and attacks you," Roberts said, "first you've got to figure out where he's attacking you. If it's in one of your marginal, second-tier states, you might want to go in and try and save face there." In coming days, some campaigns may be placing orders, and perhaps even making light buys, as a way of tricking the opposition into wasting precious resources on a market where the battle is not really to be joined.

Once all the demographic and polling data have been digested and analyzed, it still comes down to hard choices and inspired guesses. In the end, the battle may be won on sheer gut.