Floyd K. Haskell (D-Colo.) seems a classic example of the imcumbent senator facing a tough reelection campaign - a familiar character on the public stage of this political capital. In a series of reports, The Washington Post is observing his performance.

When a relatively unknown former Republican state legislator in Colorado named Floyd Haskell first ran for the Senate in 1972 as a Democrat, his campaign committee was called "People for Haskell."

This summer, when the political consultants Haskell hired to help him run for reelection were pondering possible ideas for this campaign, they had a brainstorm. Why not, they thought, use a new slogan for 1978 - "Haskell for People."

"Creative minds as work," joked Jill Buckley, a partner in the firm of Rothstein-Buckley that is handling the Haskell campaign.

Her remark was self-mocking, but in fact the new slogan was just the note Haskell and his campaign aides were hoping to strike. This looks like a year when the voters are inclined to vent their frustrations by turning out sitting politicians. The Haskell campaign wanted to find a way to advertise their man as a commodity too valuable for the voters of Colorado to squander in a fit of frustration.

So the first batch of 30-second television spots that Rothstein-Buckley produced for broadcast in August and September emphasized what Haskell has done - or thinks he has done - for Coloradans, and each on ended with a montage of faces and the words "Haskell for People."

Judging by those 30-second spots, Floyd Haskell is a warm, personable fellow who has an almost automatic rapport with his constituents. In fact, Haskell is a warm but extraordinarily laid-back politician who is downright shy in the presence of people he doesn't know, a man whose lack of back-slapping political skills has been a constant exasperation to his staff.

"He's not politician," observed Colorado's governor, Dick Lamm, who is also running for reelection this year. Lamm made the comment after a huge Democratic dinner in Colorado at which Haskell arrived late and left as soon as the last speech ended, missing any chance to shake hands with the 600 people present.

But as a statistical matter only a small handful of Colorado voters will directly experience Floyd Haskell's shy personal manner, whereas nearly all of them - if Rothstein-Buckley succeed in buying the right television time for their spots - will see the warm and friendly Haskell in the TV ads.

Rothstein-Buckley, operating out of the top floor of a house on M Street in Georgetown, provide Haskell's primary link to the voters of Colorado. Precisely because the senator himself is an unassuming, unaggressive sort, he must rely on his consultants' efforts and the local news media in Colorado to convey an impressive that will persuade a majority to want to keep him in office.

Haskell has been thinking about his need for a good media campaign for a long time. In 1976 he was struck by the success of an advertising campaign mounted by opponents of a referendum on the Colorado ballot that would have outlawed most throwaway containers.

Polls in May 1976 indicated that this idea appealed to a 2-to-1 majority of Coloradans, but in November the measure was defeated at the polls. Haskell paid a call on the ad agency that mounted the campaign against the referendum, thinking he might want to hire it for his reelection campaign.

The firm admitted to him that the anti-throwaways position was an appealing one in the state, so its objective was to find a way to work around its popularity. "They developed a slogan that said Right Idea, Wrong Solution," Haskell recalls. Then they had to think of someone to convey this message. "If only Will Rogers were still alive," one of the ad men said - and another suggested Will Rogers Jr. He did the ads and the referendum was defeated.

The ingenuity of this appealed enormously to Haskell, but eventually the senator decided that he would be more comfortable with Rothstein-Buckley. Joe Rothstein is a former administrative assistant to Sen. Mike Gravel (D-Alaska). Jill Buckley, fomerly from New York, was living in Colorado in 1972 when she met Rothstein, who was managing Haskell's original senate campaign.

It is hard to imagine that the firm who hit on Will Rogers Jr. could have done Haskell ads any more effective than Rothstein-Buckley do.

For example, Haskell adopted a technique first used in Iowa several years ago of working in varioys Colorado business establishments for a few hours to meet ordinary citizens - and get media exposure. Aides said the gimmick was marginally useful. But Rothstein-Buckley filmed Haskell packaging supermarket groceries and pumping gasoline, and they have produced a sharply focused 30-second ad that suggests a sleeves-up man of the people who is regularly hanging out with his constituents.

Another 30-second spot concerns federally financed water projects in the state. Haskell's Republican opponent is already trying to brand him as an appendage of Jimmy Carter, but Rothstein-Buckley's water project ad emphasizes the fact that Haskell has been "fighting for projects named to the president's 'hit list'," and the message sticks.

Rothstein-Buckley also sent people around Colorado to find citizens whom Haskell's office has helped during the past six years. Their true-life testimonials became the basis for a series of radio ads that repeated the message that Haskell gets things done for the home folks. Any incumbent congressman could probably find people to make similar testimonials, but the ads seem extremely effective.

Rothstein and Buckley say they will only work for candidates they really believe in, and will take on only a few in each election year. This fall they are keeping Haskell, a gubernatorial candidate in Nevada and another in South Dakota, and House candidates in South Dakota, Arkansas, Michigan, Alaska and Virginia (Rep. Joseph L. Fisher of Arlington). All of them are progressive democrats.

Haskell is a special politician for Rothstein and Buckley, because they originally met when he first ran for the Senate, and because Rothstein ran his first campaign. They acknowledge that they are not experts at running a campaign for an incumbent - outsider challengers have been their specialty.

Conventional wisdom among politicians in Colorado is that Haskell could easily be beaten in November. Failure to make a strong impression as a senator and identification with some liberal causes that many politicians believe are now unpopular are described as serious liabilities, and his opponent, Rep. William L. Armstrong, is expected to be well financed by national organizations.

But Rothstein and Buckley confidently declare that Haskell's record is one that Coloradans will approve, if they know what it is. They regard arch-conservative Armstrong - a born-again Christian and persistent "no" voter on the House floor - as vulnerable, again if people know his record.

The "Haskell for People" ads that ran in late summer are now being supplanted by ads that compare Haskell's and Armstrong's congressional votes.

The first newspaper ad of this kind, for example, notes that Haskell has supported strict controls on auto emmissions - potentially an issue in populous Denver, where a "brown cloud" of pollution has lately become a subject of concern - whereas Armstrong voted for looser emision controls. The ad boasts that Haskell was strongly behind Older Americans' Act, whereas Armstrong voted against it. New radio spots also make these comparisons, noting: "It's all in the official record."

But Rothstein-Buckley will not stick entirely to issues for the remainder of the media campaign. New five-minute and 30-minute films called "Floyd Hasakell, a senator for people" have just been completed and are being broadcast in Colorado now. These emphasize some of the themes of the earlier "Haskell for people" ads, and also try to respond to actual or anticipated positions by Armstrong.

For example, Armstrong's television advertising in his primary campaign against Apollo 13 astronaut Jack Swigert - produced by media consultant Stephen Ailes, famous for his work in Nixon campaigns among others - was what the professionals call "soft," making much of Armstrong's big, handsome family. So the new Rothstein-Buckley films show Haskell at play with his three grown daughters (Haskell is divorced) in appealing scenes.

Rothstein and Buckley expect Armstrong to try to brand their man as soft on issues of national defense, so the new 30-minute films include snapshots taken by a young Floyd Haskell when he landed at Nagasaki, Japan, just days after the atom bomb fell there. These are followed by interview in which the senator says he knows the effects of nuclear weapons and emphasizes the need to reach arms control agreements. "Of course, we must have a strong national defense," Haskell adds.

In a recent interview, Haskell expressed satisfaction with the advertisements Rothstein-Buckley have produced. "The only thing that's disturbing is whether people will pay attention," he said almost ruefully.

Haskell acknowledged that he now has to rely on someone other than himself - i.e., Rothstein and Buckely - to convey to the public the strongest image it is likely to get of Floyd Haskell. Of course, he added, the consultants cannot create that image out of whole cloth - it has to be based on what he has really done and what he is really like.

By the end of October, according to Haskell campaign aides, the senator's campaign committee will have spent more than $90,000 on Rothstein-Buckley's services, including reimbursements for the firm's expenses.