The National Education Association, one of the most politically powerful unions in the country, today announced plans to pour as much as $1 million, and thousands of trained political operatives, into the 1982 congressional campaigns in an effort to undercut President Reagan's support in Congress.

At a press conference this morning, NEA executive director Terry Herndon described the Reagan administration as "the worst administration in the history of the republic as far as public education is concerned." Herndon said that if Reagan is allowed to make the cuts he desires in public education funds, and gets his proposed tuition tax-credit plan approved, public schools will become "nothing but storage halls for poor peoples' children."

After the press conference, an estimated 3,000 teachers here for the NEA's annual convention marched through downtown Los Angeles, chanting, "Teacher power!" to protest cuts in public education funds.

Ken Melley, the NEA's political affairs director, said in an interview that the union's political goal is "to do our level best to bring about a Congress in 1982 that is favorably disposed toward public education."

As the final session of the six-day convention began this morning, delegates had contributed $90,000 to the union's political action fund, bringing the year's total to $780,000. Melley said the union leadership was confident that a fund-raiser planned for today would bring the total to $1 million.

That money will be given to the 109 House and 22 Senate candidates the NEA has endorsed in the 1982 elections. Candidates in targeted races will be given $5,000, the maximum donation allowed by law.

In addition, the NEA has begun a program to train teachers as professional political operatives, with expertise in telephone banks, polling and getting out the vote, to work for endorsed candidates. Melley said he hoped there would be as many as 200 of these trained workers in each targeted race.

In the 1980 presidential campaign, the NEA threw its considerable resources behind then-President Carter. After the election a poll of NEA members taken by the union disclosed that 41 percent had voted for Reagan, and only 44 percent supported Carter.

But conversations with rank-and-file union members around the convention hall--including those who supported Reagan in 1980--did not disclose any dissatisfaction with the union's endorsing process.

For instance, Julio Perez, a language teacher from Bessemer, Ala., said that he voted for Reagan "after balancing my pocketbook with my country," and deciding the country needed Reagan more than his pocketbook needed Carter.

Perez said that, while his union's support of Carter made him "unhappy," it did not make him uncomfortable because the endorsing process is so democratic. NEA endorsements are made by a majority vote of members of local political action committees, which are open to any union member who wants to join.

"It's a free country," said Perez, "and everybody has a right to support who they want. The endorsments are decided democratically."

Melley said that the NEA leadership hopes to convince its rank and file that it is in their interest, both economically and socially, to vote in 1982 for congressional candidates, mostly Democrats, who support public education. He added that, after the 1982 elections, the union will "work like heck in '84 to kick him Reagan out of office."