The nearly 8,000 teachers at the National Education Association convention here may be united in their resentment of President Reagan, but none of the Democratic presidential candidates who came to polish the apple for them has been able to turn that emotion to his own advantage.

"Our job now is to fire the delegates up in a way that is useful to direct and focus their frustration," said Ken Melley, the NEA political director.

In seeking NEA support in 1984, Sen. Ernest F. Hollings (D-S.C.) made the top bid with a $14 billion education proposal, but NEA officials are not impressed.

"We're not going to run to somebody just because they put forth a $14 billion program," said Mary Hatwood Futrell, who is running unopposed for the NEA presidency.

Holling's proposal is viewed as "something that will never happen," another official said.

Former vice president Walter F. Mondale's proposed $11 billion program doesn't address the issue of teacher pay directly, Melley observed, but leaves it to the communities. Only Sen. John Glenn's (D-Ohio) $7 billion plan seems realistic to many of the teachers and earmarks money specifically for pay increases.

Even so, the delegates are under- whelmed.

"It's only a very small step, providing $1,000 each for 25,000 teachers when there are 3 million teachers in the country," Melley said.

The teachers' fervent desire to get rid of Reagan has made the question of "winnability" especially important, NEA officials said.

Mondale is still the odds-on favorite for the NEA endorsement because of the constancy of his support on education issues.

But Glenn's recent advances in the polls got the delegates' attention and his friendly manner and enthusiastic delivery of his message won their praise.

"A lot of these people haven't seen him in a couple of years," a Glenn aide said. "Now he's had the benefit of hundreds of stump speeches and he's having more fun at this."

On the videotape that Glenn, like the other candidates, prepared for the delegates, he seemed relaxed and free of his old rigidity.

Hollings drew praise for strongly opposing tuition tax credits, which he alone of the candidates has done, Melley said.

Sen. Gary Hart (D-Colo.) attracted warm crowds and praise for his strong support of the American Defense Education Act, which he introduced in the Senate and which would offer incentives to school districts to improve math, science and other courses.

In order for the NEA to decide whom to endorse by its self-imposed Oct. 3 deadline, Melley said, "We'll probably get to the point of putting their feet to the fire on specifics" of such issues as tuition tax credits and merit pay for teachers.

That will be done by Futrell in videotaped interviews scheduled for August with each candidate.

The candidates are attentive to the NEA because the 1.7 million-member union is a power in the Democratic Party. In 1976 it helped elect Jimmy Carter, and in 1980 its members comprised the largest single block at the Democratic convention, with 10 percent of the delegates and alternates.

The NEA claims an average of more than 4,000 members in every congressional district. This geographical distribution, plus the fact that its members are generally well-educated and known in their communities, makes the union one of the most effective grass-roots political organizations in the country.

Still, the NEA, like other organizations, has trouble delivering its members to a candidate. It endorsed Carter early in his 1980 reelection campaign, but an NEA poll later showed that 41 percent of its members voted for Reagan.

Compared with most other unions, the NEA's democratic procedures are extensive and open, but the delegates here won't vote directly on their choice of a candidate to support in the primaries. The union's board of directors is scheduled to decide that.