Virginia Democrat Charles S. Robb, in an abrupt reversal of campaign strategy, launched a direct attack on Republican J. Marshall Coleman today, accusing him of spreading "misrepresentations, misconceptions and red herrings" in their race for governor.

The worst distortion, Robb said, was Coleman's attempt to portray him as a closet believer in big government because of his ties to late President Lyndon Johnson whose daughter, Lynda, he married.

"Fathers-in-law are not an issue in this campaign and I know you don't want to make mothers-in-law an issue," Robb said, referring to the fact that Coleman's mother-in-law has said publicly that she is supporting Robb.

During a joint appearance, Robb challenged Coleman to defend his earlier charges about Robb's purported allegiance to federal social programs developed as part of Johnson's Great Society program. "Those claims simply aren't true and, Marshall, you know they're not true," Robb said.

The real issue of the campaign, Robb added, is "Which of us are responsible enough to be governor, trustworthy enough to be governor and mature enough to be governor." Robb suggested that Coleman should not be trusted with the governorship.

The attack by Robb, the state's lieutenant governor, at a breakfast session of more than 100 Virginian newspaper publishers and editors, appeared to catch Coleman off guard.

Coleman, the state's attorney general, made no direct attempt at rebuttal, but instead gave a prepared address repeatedly emphasizing his support of President Reagan and trying to distance himself from Robb on taxes, criminal sentencing and investment of state retirement funds.

As after their previous confrontation, both sides claimed victory. But the Robb camp clearly was elated, believing it had called Coleman to task while stressing Robb's main theme of trustworthiness.

The feeling of many in the audience was that Robb had come on stronger, although Coleman recouped to some extent with his handling of questions from the floor. "I though Marshall should have responded [to Robb's charges] instead of going with his pat speech," said John Leard, executive editor of Richmond's two daily newspapers.

In recent Virginia elections, the state's editorial pages have overwhelmingly favored conservative Republicans over moderate or liberal Democrats. But this year, many appear to be fence straddling, either because of Robb's conservativism is appealing or because they are not satisfied with Coleman's conservative credentials.

"It's gong to be a very close call as far as we're concerned," said J. Stewart Bryan, publisher of the Richmond newspapers, considered among the state's most influential and conservative. As for today's debate, Bryan said, "Marshall appeared smoother but I personally liked Robb's approach to taxes better. For Marshall to say he'll veto any tax increase under any circumstances almost borders on irresponsible."

In earlier debates and on the campaign trail, Robb has often appeared reluctant to mention Coleman by name, let alone directly attack him. Robb's advisers were privately critical of what they saw as his lackluster appearance in a television debate with Coleman two weeks ago.

By contrast, Coleman, who has trailed Robb in name recognition polls, has from the opening of his campaign and in his television and radio ads struck personally at Robb.

Today the tables were turned. Robb aimed sharp and frequent remarks at a number of Coleman campaign themes, among them charges that Robb was a big spender who plans to win the election by flooding Virginia with out-of-state campaign money, then raise state taxes to pay for expensive new social programs.

To a recent Coleman claim that Robb has journeyed to California to raise funds, Robb replied he had made no such trip. "I will admit to you quite candidly my two eldest daughters were in California, but I assure you they weren't raising money they were spending it."

As for another Coleman charge that Robb had doubled the staff of the lieutenant governor's office, Robb responded that his office's entire annual budget was less than the salaries of Coleman and Anson Franklin, Coleman's former top aid in the attorney general's office. Franklin is now Coleman's campaign manager.

Afterward Coleman said he had stuck to his script and avoided responding to Robb's attacks because "I thought they were kind of silly -- I thought we were here to talk about our concept of the office."

Robb said he did not plan to make the attacks a constant campaign feature. "I had a long list of things I thought needed clearing up and this seemed like a good opportunity to do that," he said.