The students of Texas A&I University are having an outdoor barbecue on a chilly Wednesday night here when Bob Armstrong, the Democratic land commissioner and a candidate for governor, arrives. Hardly a head turns.

A day later, several hundred members of the Texas Senior Citizens Council are eating dinner in a San Antonio hotel. Almost obscured behind a group of madrigal singers stands Texas railroad commissioner Buddy Temple, a solitary figure peering out from the head table. Temple is here campaigning for governor.

In the northeast Texas town of Greenville, state Attorney General Mark White has just finished a reception in the county courthouse. He enters the main hall, where a group of prospective jurors are taking a break. Hardly anyone comes forward to meet a man who wants to be the next governor of Texas.

The scenes are typical of the campaign here. Only a few days remain before the primary Saturday, but the Democratic candidates for governor are having trouble getting the voters' attention. One reason is Republican Gov. Bill Clements.

For the first time in modern memory, Democrats will vote in a primary without any confidence that their nominee will be elected governor in November. Four years ago, Clements spent $7 million to break a century-long Democratic stranglehold on the governor's office, and he is prepared to invest that much again to hold onto it.

As a result, the Democratic gubernatorial primary, once the scene of divisive and decisive campaigns, is today an uninspiring warm-up among three statewide officeholders, each trying to prove that only he can defeat Clements.

White is the leader in the polls, followed by Temple and Armstrong. White has said he might win the nomination outright on Saturday but most experts expect the nomination to be decided by a runoff June 5.

"The Kentucky Derby isn't being held in May this year," White said of the apathy about the primary. "It's in November. People have a different attitude toward the race because of it."

Some powerful Democratic groups decided to sit out the primary. The Texas AFL-CIO and the Texas State Teachers Association did not endorse anyone in the gubernatorial race, preferring to unite behind whoever is the eventual nominee.

Money is scarce, as some major contributors await the outcome of the primary and others line up behind Clements. "Giving to a Democratic nominee doesn't guarantee you'll be with the winner," Armstrong said.

All three major candidates have borrowed to finance their campaigns. Temple lent himself $1 million of an estimated budget of $1.4 million. White will spend about $1.2 million and Armstrong up to $500,000. Last fall, some experts predicted the primary campaigns would cost between $2 million and $3 million each.

The Democrats also seem to be looking over their shoulders. "The candidates are a little scared," said Joe Gagen, executive director of the Texas Democratic Party. "They don't want what they say to come back and haunt them in the fall."

Because of all this, the public has refused to become interested. Polls taken on behalf of several candidates showed roughly half the prospective Democratic voters were undecided in early April.

White, 41, is the most conservative of the three and argues that his conservatism is the key to beating Clements. "I'm not vulnerable on the magic issues of crime, taxes and labor," he said.

A Houston lawyer, he was appointed secretary of state by former governor Dolph Briscoe, then ran for attorney general in 1978. He upset a liberal candidate in the Democratic primary and went on to defeat James A. Baker III, now White House chief of staff, in the general election.

White has clashed repeatedly with Clements over the handling of the federal lawsuit against the Texas prison system and other issues, and as a result he is the Democrat whom Republicans would most like to beat up on in the fall.

Armstrong, 49, a former state representative, was elected land commissioner in 1970 and has built a record of balancing the interests of environmentalists and the oil and gas industry. He argues that he has the best record to match against Clements and the personal popularity to motivate regular Democrats to work in the fall campaign.

A well-liked and tireless Democratic Party worker, he was cochairman of George McGovern's campaign in Texas in 1972 when most other Democrats refused to get involved. Since then, he has tried to live down charges that he is a liberal.

His work in behalf of the party prompted the London Economist to tag him a Democratic George Bush. "I went out and applied for a Brooks Brothers credit card," he joked.

Temple, 39, served four terms in the Statehouse before defeating an incumbent Democrat to gain a seat on the Texas Railroad Commission in 1980. He jumped into the governor's race a few minutes before the filing deadline in February, claiming the other candidates had not generated any enthusiasm. "We haven't lit any fires either," his campaign manager Tony Proffitt conceded.

A moderate, Temple believes he would be most acceptable to the various factions of the Texas Democratic Party.

The appearance of money is both his greatest strength and biggest liability. He is the son of Arthur Temple, a major stockholder of Time, Inc., and head of the timber and paper conglomerate, Temple-Eastex Industries. Many Democrats assume that, if he wins the primary, Temple will dip into the family fortune to match Clements dollar for dollar in the fall, but he has denied it.

"I have neither the ability nor the inclination to do that," Temple said.

In public, the three sound as if they had based their campaigns on the same analysis of public opinion. Education is their top priority, and all favor higher salaries for teachers, a promise designed to generate enthusiastic campaign workers in the fall. White also stresses discipline in the classrooms. Crime is their second priority, with all advocating spending more on law enforcement.

To establish their own identities, the candidates have taken to name-calling, causing former White House press secretary George Christian to quip, "It's becoming a typical Democratic primary. They're starting to get mean."

White and Temple are spending about two-thirds of their budgets on TV ads and are exchanging electronic charges--some of which are accurate--on a regular basis. White's ads prompted Temple to call the attorney general the "Pinocchio of Texas politics."

Armstrong is hoping to benefit from all this by persuading voters that the only manure on his clothes is from the cattle he raises in central Texas.

Meanwhile, the candidates are trying to drum up support any way they can.

When White was in Greenville last week, his car was stopped by a long freight train rumbling through town.

As traffic piled up behind him, White suddenly hopped out and rapped on the window of the car in the next lane. An elderly man rolled down his window a little way and White thrust his hand through the opening.

"I'm Mark White," he boomed out. "I'm running for governor." Then he motioned toward the freight train. "I'm going to get you an overpass."