Harry Roe Hughes was leaving a political forum in Dundalk late on the night of Aug. 19 when his campaign manager came running up to him with an early street edition of the next morning's Baltimore Sun.

"You got it! You got it!" shouted Joseph Coale, his hands gripping an editorial that in glowing terms endorsed Hughes for the Democratic nomination for governor in Maryland. "Look at this, Harry. Take a look at this!"

Here was a moment that begged for celebration. Dismissed by the pulse-takers, avoided by the political financiers, generally portrayed as a decent and smart man who could not win, Hughes now had been embraced by a newspaper with vast influence in the state. He had every reason to be insufferably happy and dramatic.

Hughes, however, is not an excitable fellow. He examined the editorial, smiled, and said: "Isn't that great." Then, after a few minutes of calm discussion, he got into his silver Chrysler, LeBaron and drove to his home in Baltimore's Cross Keys neighborhood for a sound sleep.

That's the way it is with Harry," said Coale, a young stockbroker who has sometimes taken to making animal noises and adding the prefix "poo" to words to enliven the campaign atmosphere. "He doesn't seem to have very high highs and low lows. The man is incredibly straight and steady."

These are the qualities that Harry Hughes has carried with him for 51 years, from his childhood on Maryland's Eastern Shore to his 16 years in the General Assembly to his six years as the state's first transportation secretary to the last years as a candidate for governor.

He has a reputation as a straightforward, thoughtful and honest person whose few personal deceits are on the level of bumming cigarettes and not telling his wife and two daughters that he still smokes. But along with that reputation come the perceptions that Hughes is too reserved, modest and dull to capture the imagination of the voters.

"It seems you have to be a throwback to P.T. Barnum to get ahead in politics these days - look at Jerry Brown and Ted Venetoulis and Louis Goldstein (the fast-talking state comptroller)," said Tax Commissioner John Logan, an old friend from Hughes' hometown, Denton, the county seat of Caroline County. "When you guys write about a solid guy like Harry, it's like writing an obituary. He doesn't spend his life generating anecdotes."

Logan reinforced his own thought by admitting that after watching his friend for more than 40 years he could not immediately recall one anecdote or incident that would flesh out the story of Harry R. Hughes. "I know that there aren't any chinks in the armor," said Logan. "But I don't know what else I can tell you. Harry isn't too heavily into all that image crap."

To Hughes and his supporters, the question of the 1978 campaign is whether substance can prevail over image. They believe that in terms of real character and accomplishment Hughes is superior to his three primary opponents - Acting Gov. Blair Lee III, Baltimore County Executive Theodore G. Venetoulis and Baltimore City Council President Walter S. Orlinsky.

The accomplishments by which Hughes is asking to be judged stretch back 22 years and encompass his service in both the legislative and administrative branches of government, starting with his election to the House of Delegates at age 25 in 1954.

During his four years in the House and 10 years in the state Senate, Hughes was considered one of the more conscientious and intelligent legislators someone who actually understood the finer points of budgets and tax matters.

"There weren't that many bright lights in the legislature in those days," recalled attorney Alexander Stark, a former delegate from Baltimore who is now supporting Hughes in his race for governor. "I didn't know Harry very well, but we all knew that he was one of the few guys you could turn to for smart advice."

Stark and other legislators from Baltimore were also impressed by the fact that Hughes, despite his roots in the rural and conservative Eastern Shore, was in the forefront of attempts to restructure the state tax system to the benefit of the urban centers. As chairman of the Senate Finance Committee, Hughes coauthored the first tax reform package in the state's postwar history. Known as the Cooper-Hughes bill, it set up the tax structure that supplied the counties and Baltimore City with income tax revenues to supplement their property taxes.

Hughes also gained the respect of civil rights activists as one of only two senators from the Eastern Shore - a region with a long history of segregation - to vote for bills opening up public accommodations to blacks and striking from the books a law prohibiting miscegenation.

"Some of the old-timers thought Harry was a bit on the liberal side (because of his support for the civil rights measures), but he was so honest and thorough about it that he was never in hot water over here," said Logan, himself a former Caroline County delegate. "Harry led the transition from the old days to the new."

During his four years as chairman of the finance committee, Hughes sat next to a senator from Montgomery County named Blair Lee III. Lee himself now concedes that Hughes was the more active of the two. "But he wasn't perfect," the acting governor informed a recent audience during a campaign that finds the former colleagues running against each other. "Harry was always filching my cigarettes."

After 12 years in the Senate, Hughes decided not to seek reelection in 1970. Hughes said he left Annapolis because "I had done as much as I wanted to there." Another legislative activist during that era offered a different perspective. "Harry had been shining for 10 years, but by the time he got out his light was beginning to fade," he recalled. "He was sharp in comparison to the neanderthals of the 1950s, but there was a new breed coming in. Suddenly, there were a lot of people as smart as Harry Hughes."

The two failures of Hughes' career during his legislative days involved his attempts to move out or up. In 1964, he ran for the Eastern Shore congressional seat but lost to Republican Rep. Rogers C. B. Morton. Four years later, when Spiro T. Agnew resigned to become vice president, Hughes offered himself as a candidate for governor. The General Assembly, which then had the power to select Agnew's successor, chose House Speaker Marvin Mandel.

In 1971, on the eve of the first legislative session Hughes would miss in 16 years, Gov. Mandel chose Hughes to become the state's first secretary of transportation, a task that involved running such hitherto independent and antagonistic agencies as the state Roads Commission, Maryland Port Authority, Baltimore Metropolitan Transit Authority, Department of Motor Vehicles and the Aviation Commission.

Many state Democratic observers speculated then and later that Mandel's selection of Hughes was calculated to remove the tall, handsome Eastern Shore politician from the gubernatorial scene. "I don't know whether Marvin was trying to co-opt me or not," Hughes said recently. "But it doesn't matter, the way I look at it. I had it in my mind that the job would be fascinating."

In any case, the appointment brought with it a change in life style as well as employment for Hughes. He moved from Denton, a town of 1,600 where there were more soybean farms and tomato canning plants than lawyers, to Baltimore, the largest city in the state. There, he was quickly accepted by such leaders of the entrenched legal establishment as H. Vernon Eney and Eli Frank, became a member of the elegant Greenspring Country Club, and joined a downtown organization of city movers and shakers known as the Center Club.

Because of these associations and his own refined style, Hughes is sometimes mistaken as a "blueblood," a man born into wealth and upper-class snobbery. He is actually the son of a schoolteacher and stockroom manager. As a boy he played baseball, not polo. (Hughes was a good enough pitcher to be signed by the New York Yankees. He played ball for a year in the class D Eastern Shore League).

One of his ancestors on the Roe side was a U.S. senator in Delaware; his great-grandfather and grandfather on the Hughes side were state senators. None was particularly wealthy (Harry, who has earned between $50,000 and $75,000 a year for the past 15 years but has no major stock or land holdings, is the richest of the lot), nor were they snobs. "My family had a history of open-mindedness," said Hughes. "The word 'nigger' was never allowed."

Hughes came to the Transportation Department with little administrative experience and no expertise in the field. He inherited a roads department that, he now says, "had been overpromising and overprogramming for 20 years." The reviews of how Hughes handled the department over the next six years are mixed.

"There may have been some people who could have handled the administrative aspects of it better," said J. Michael McWilliams, a Baltimore attorney who served as the department's general counsel. "But as a diplomat and mediator - the toughest parts of the job - he did as well as anyone could have."

Hughes himself thought well enough of the job he was doing to let Jimmy Carter's aides know that he would be interested in the federal transportation secretary's post in 1976."I had learned a lot in six years and was ready to handle it on the national level," Hughes said. "But nothing came of it."

The one thing that people remember most about Hughes' tenure as transportation secretary is the manner in which he quit.

As part of his effort to keep the department clear of the cronyism and corruption that had plagued state government for decades. Hughes set up special selection committees to review all major contract proposals. In 1977, Hughes became concerned that the selection process was being tampered with on the Baltimore subway contract.

The selection panel's recommendation was being ignored, he feared, because Victor Frenkil, a major Baltimore contractor who contributed heavily to Democratic campaigns in the state, failed to receive the recommendation and was attempting to pressure his way back into the action. On May 26, after the state Board of Public Works rejected the firm recommended by the selection committee, Hughes resigned "as a matter of principle."

It was a matter of weeks before Hughes began preparing his race for governor, a race in which he would portray himself as a politician who had maintained his integrity in the midst of corruption. Although some of his critics say that Hughes' resignation was politically motivated, no one has questioned the notion that Hughes left office untouched by the scandals of the Mandel administration.

It is integrity, more than anything else, that Harry Hughes wants the people to remember about him when they vote Sept. 12. The message has been blunted by Hughes' lack of money - his campaign treasury has never had more than $150,000 - and by his own reserved nature.