Ronald Reagan stepped up his drive for union votes today in a campaign swing that made some of his past policy views seem as obsolescent and abandoned as the shutdown steel plants he visited here.

Drawing a mostly friendly reception -- and a few protest pickets -- from many of the remaining 500 workers in the eyesore shells of what once were busy rolling mills and blast furnaces, Reagan blamed the decline of the steel industry on the Carter administration's weak resistance to foreign imports and its excessive zeal for environmental controls.

In a related development, the executive board of the Teamsters union endorsed Reagan for president today in a unanimous vote. The Teamsters, America's largest labor union with 2.3 million members, is the first major union to back Reagan.

As Reagan toured the steel works here, volunteers passed out a new labor pamphlet, prepared by Michael Balzano, Reagan's newly named labor consultant and former director of the Action agency in the Nixon administration. Balzano said he had had "a hell of a battle" getting the pamphlet approved by the Reagan organization, but said its contents carried the personal approval of the candidate.

The fierceness of the struggle was no greater than the distance Reagan has traveled from some of his past positions.

Carrying the slogan, "Elect A Former Union President, President," a reference to Reagan's six years as head of the Screen Actors Guild, the flyer says that "Carter and his Washington supporters are trying to scare union members . . . so let's set the record straight. Governor Reagan is not antiunion."

The flyer says that Reagan would not seek to abolish the Occupational Safety and Health Administration, would not seek a national right-to-work law, and would not extend antitrust laws to labor unions or seek repeal of the Davis-Bacon Act, requiring that federal contractors pay prevailing wages.

In an April 1979 radio broadcast, Reagan said "Amen" to a bill proposing the abolition of OSHA and last March 31 said, "I question seriously" the need for the agency.

Last April 22, he said that labor union leaders had so much power that "we should look very closely at whether they should not be brought under antitrust laws."

In an October 1978 newspaper column, Reagan said, "Davis-Bacon is a needless burden on local taxpayers, a gift of tax funds to the privileged workers."

In the new flyer, Reagan said he would seek to "reform" OSHA and "tighten up the administration" of Davis-Bacon -- but not do away with them.

Martin Anderson, Reagan's chief domestic issues adviser, said, "He is not changing his positions. There is a difference in emphasis. He is discussing these issues more sharply and definitively."

Speaking in a largely abandoned and rusting Jones and Laughlin plant in the Mahoning Valley, where 13,000 steel jobs have been lost in the last three years, Reagan told the workers:

"We've got to protect this industry and all industries against dumping" of below-cost foreign steel in the U.S. market, "and we've got to get rid of those thousands of regulations that make it impossible for us to compete" with Japanese and European producers.

On Thursday, Reagan will carry his blue-collar campaign to the convention in St. Louis of the National Maritime Union, which represents workers in another industry where America has a hard time competing.

Last night in Steubenville and Youngstown, the Republican nominee met with local officials of mine workers, auto workers and steel workers unions in what Balzano called an effort "to take the message straight to the union halls and combat the propaganda that Reagan is antiunion."

Today he delivered a speech on education at Wheaton College, a fundamentalist school in heavily Republican DuPage County, a Chicago suburb where Carter had campaigned Monday.

Once again, he softened or omitted some of his past policy views.

A long-time critic of federal aid to education, Reagan repeated his view that state and local control of schools is essential.

But he added that "the federal government does have an important -- if not central -- role in our educational system," and vowed that as president he would vigorously support federal action against "intentional discrimination" in education.

Rather than proposing wholesale abolition of federal aid to education, he said he would name a citizens task force to evaluate current programs, promising to "keep the ones that are working and get rid of those that are not."

Earlier this year, Reagan often asserted that federal aid meant federal control and called for abolition of the Department of Education. Today, he said it would be "naive not to be concerned" that the department might take over such matters as the accreditation of schools -- but he said nothing about abolishing the department.

In places like DuPage County, Reagan is battling for ticket-splitter votes with both Carter and independent candidate John B. Anderson, and his more doctrinaire conservative positions have been a problem for his campaign workers in making converts.