Political consultant Keith Haller's calendar for Feb. 24 traces the whirlwind path of change that he is carving on Maryland politics.

For 12 hours that snowy Monday, the Bethesda pollster crossed the state to meet with clients Alex Williams, a lawyer who wants to be elected Prince George's County state's attorney this fall; Sidney Kramer, who is running for Montgomery County executive; Democratic Rep. Michael D. Barnes, a U.S. Senate candidate, and Anne Arundel County Executive James Lighthizer.

Those four politicians are as different as Democrats get in Maryland, but their common demand for Haller's blend of old-fashioned shoe leather and modern election techniques helps explain why the intense New York native is the most sought-after political operative in the Baltimore-Washington corridor.

Haller has engineered a string of election victories, chiefly by taking sophisticated computer analyses of voting trends and applying the data to target glossy mailings directed to those most likely to vote in Democratic primaries and general elections. By crafting local campaigns with the standard tools of national elections, he is single-handedly reshaping the business of getting elected in Maryland, his clients say.

So striking is his success rate -- he was the mastermind behind Barnes' election to Congress in 1978, Lighthizer's win in 1982, the defeat of a hotly contested referendum in 1984 and Rockville Mayor Steven Van Grack's election last fall -- that about 20 Maryland politicians are now buying or begging for Haller's time and advice.

Today, six months before the Democrats' Sept. 9 primary, state Sen. Stewart Bainum Jr., who is running for Barnes' seat in the House of Representatives, three hopefuls for the state Senate and at least one candidate for the Montgomery County Council are paying thousands of dollars for the services of Haller's privately held Potomac Survey Research Inc. (PSR).

Last night, at a gathering of several hundred Democrats in Baltimore County, national party chairman Paul G. Kirk praised Haller's labors on behalf of the Maryland party -- the creation of a massive voter data bank to return a state that voted for President Reagan in 1984 to the Democratic fold by 1988.

"Keith can make the difference in winning or losing," said Del. Ida G. Ruben (D-Montgomery), a state Senate candidate who expects to spend roughly $20,000 on PSR services this year.

The firm is a place where politicians can do one-stop shopping for a wide range of campaign services. Haller, his associate Linda Katz, who is a graphics designer, and their stable of artists, production people, printers, data processors and mail experts can quickly manufacture all the conventional stuff of campaigns -- eye-catching literature, bumper stickers, buttons and fund-raising mailers. The cost of such a package can vary widely, but generally it is between $5,000 and $10,000, according to PSR customers.

PSR's main strength, however, is its precinct-by-precinct voter data, which, coupled with Haller's energy and strong grasp of back yard issues, make the firm especially popular this year, when nearly all Maryland officeholders are up for election.

"Two things make him good," said Bainum, who is in a five-way race for the Democratic nomination in the 8th Congressional District. "The first is his fertile and creative mind -- you never have the time, money, or resources to do half his ideas. The other is his numbers. Keith has very good numbers."

PSR's telephone surveys of 200 to 600 voters produce a statistical sample that can tell Haller's clients which issues matter in an election and where a candidate is strongest.

Moreover, such polls, especially those that screen people most likely to vote in a primary or general election, can pinpoint a candidate's geographic and ideological weaknesses -- crucial variables in elections that are often won or lost on the basis of public perception.

Repeatedly during the past seven years, Haller's wizardry at refining poll data has served as the basis for his candidates' successes. Some examples:

*In 1978, as Barnes campaigned to unseat popular Republican Rep. Newton I. Steers Jr., Haller's data showed an untapped reservoir of "persuadables" -- Democrats who frequently voted Republican -- in the affluent 16th legislative district around Bethesda.

Barnes focused nearly all of his efforts on those ticket-splitting precincts in a swath from the Potomac River to Rockville, and he defeated Steers with 52 percent of the vote.

*In 1981, before a special congressional election in Maryland's 5th District, which includes much of Prince George's County, several private polls showed Democrat Steny H. Hoyer trailing badly in a crowded pack of primary candidates.

But PSR's poll for Hoyer found unsually high support for him among those likely to vote, so he targeted his efforts to those prime voters. Hoyer won the primary and, armed with a PSR prediction of a high turnout by black voters, went on to beat a well-financed Republican opponent with 55 percent of the vote.

*In March 1982, a pollster for James Lighthizer, then a state delegate who was considering running for Anne Arundel county executive, told Lighthizer he had no chance of winning a three-way primary. At the end of June, a PSR poll of prime voters showed that "the election was a . . . long way from over," Lighthizer recalled recently.

Lighthizer, whose intense media campaign was crafted by Haller and Katz, was outspent by his two primary opponents, but he still won that election with 32 percent of the vote.

*In October 1984, Haller was hired by the Montgomery County League of Women Voters to defeat a popular referendum that would have forced members of the County Council to run from electoral districts, rather than countywide.

Two weeks before the vote, PSR workers reached 15,000 voters by telephone and -- after saying that they were calling on behalf of the league -- suggested that altering the election system would deprive residents of the right to vote for all seven council members and somehow damage the generally high quality of life and public government in Montgomery.

PSR's "persuasive contact," plus a last-minute radio blitz, defeated the referendum.

"Keith fills the vacuum," said Lanny Davis, one of PSR's founders and a close friend of Haller's. "He knows practically everyone in politics in Montgomery County and the rest of the state. And by providing all the other kinds of campaign services -- creating literature and direct mail -- he's built PSR into a very critical position."

Being a pollster for the Democratic establishment is an unlikely occupation for Haller, a gravelly-voiced man who spent years fighting within his own party to end the Vietnam War. Haller, who is 38 and married, did not serve in the war because of an eardrum punctured in childhood.

"A lot of people who went through the '60s experience tend to get a little bit frustrated by the process, especially when you're working on the national level where it's difficult to measure success," Haller said.

But, he added, "I feel like I've been sitting on a powder keg. We're teaching people for the first time, and winning, by applying the same concepts, the same techniques that are common to national elections."

Still, it is sometimes difficult for Haller to keep his temper when dealing with the fragile egos of some politicians.

"Let's not make him into the Second Coming," said Van Grack, Rockville's new mayor. "Keith's downside is that sometimes he is a tough person to deal with. He can be firm, abrasive even. But I guess I'd rather he act that way than I as the candidate act like that."

Van Grack's election as mayor of Maryland's second largest city is a textbook case of Haller's hands-on approach to elections. The PSR staff painstakingly prepared all of Van Grack's campaign literature and reviewed and polished the candidate's speeches. Once Haller accompanied Van Grack as he campaigned door-to-door.

Another Haller decision was even more decisive. Early in the three-way race for mayor, Van Grack proposed to his steering committee that he jog down Rockville Pike during rush hour to dramatize the traffic congestion on the highway. But "Everybody said, 'No, no, no, the press may make you look silly,' " Van Grack recalled.

In the end, it was Haller who decided that Van Grack should risk the run. Van Grack carefully timed two practice jogs, and Haller lined up coverage by a dozen local television, radio and newspaper reporters. The press corps gave the tactic rave reviews.

For Bruce Adams, a Montgomery County Council candidate, Haller offered advice of a different kind.

Adams recalled that in February 1985, 18 months before the election, "Keith comes to me and says, 'Where's your fund-raising list?' "

Adams had no list of potential contributors. "I asked him how many people I needed, and Haller says 1,000. My knees went weak."

Nevertheless, Adams produced a list of 850 names, paid PSR $2,000 to draft and mail a fund-raising letter -- and collected $20,000, more than twice his goal.

Without Haller's edict to construct the contributor list, "I wouldn't have the base I do now," Adams said. "What Haller does is establish your credibility. He lifts you above the pack."

This year, as campaign costs approach record highs, PSR will turn its first real profit, according to several Haller associates.

Haller, who declined to say how much he makes, sometimes bemoans those ever-rising costs, but defends them as a natural part of doing business in a modern political arena.

"If I have a liability or weakness, it is that I have been on the public side for so long that I tend to approach these things in a public-spirited manner, rather than as a business," Haller said.

"I have a lot of friends who are running for office, and I feel spread thin in the sense that we're working for a lot of them," he said. "As long as we keep the energy high, we should do fine."