Virginia Republican gubernatorial nominee J. Marshall Coleman has a specific strategy for closing the gap between himself and Democrat Charles S. Robb: a greater emphasis on conservative issues, some of them racially-tinged, more negative television and radio advertising, and a few kind words from President Reagan.

Robb, the race's acknowledged front-runner, has his own plans to counterattack the Coleman offensive as the campaign enters its final nine days. Robb will continue to attack Coleman through surrogates and negative media ads, but Robb himself will emerge in a series of positive, "statesmanlike" ads. Robb's strategists hope Reagan's appearance Tuesday will solidify their own base among liberal and black voters.

The Democrats plan a voter-turnout effort that they say will be comparable to the GOP's. A major scene of the battle will be the Northern Virginia suburbs, where most politicians -- including, privately, many Republicans -- believe Robb has a substantial lead.

"If Marshall Coleman has to win my area to get elected, then go ahead and stick a knife and fork in him because he's done," said Fairfax state Sen. Richard L. Saslaw, a Democrat.

Both sides, which receive daily updates from their pollsters, agree that Coleman has cut into Robb's lead in recent weeks but disagree on how much. A Richmond Times-Dispatch poll, released today, gives Robb a nine-point edge, 47 to 38, with 15 percent still undecided.

Coleman pollster Richard Wirthlin puts the gap at 4 percent, according to a campaign memo. Robb aides say that their pollster, Peter Hart, puts the lead somewhere in between.

Both sides agree on how Robb built that lead: by appearing "gubernatorial," while painting Coleman as somehow untrustworthy and suspect. But they also agree that, despite Robb's lead, the race is much like last year's presidential election: still highly volatile, and subject to large voter swings in the closing days.

The Coleman campaign is confident that it can reproduce past Republican victories by attracting suburban voters who have yet to commit themselves to either candidate.

"The people we have to to win over are the soft conservative ticket-splitters who have voted Republican in the past," said Coleman campaign manager Anson Franklin.

Robb strategists say that even in Northern Virginia, their polls show what campaign manager David Doak calls a "big bubble" of "soft" Robb supporters and undecideds.

To sway these voters, Coleman is relying on labor and racial issues that Republicans in Virginia successfully have hammered Democrats with for more than a decade. He is emphasizing his strong support for the state's Right to Work law, while charging that Robb, who also backs the law, would not vigorously enforce it because of the Democrats' alliances with organized labor. Unions dislike the law because it prohibits mandatory union membership.

Coleman also is stressing his opposition to extension of the Voting Rights Act, the D.C. Voting Rights Amendment and voter registration by postcard -- all of which Robb supports.

Coleman television spots, in which the candidate himself appears and reiterates his differences with Robb on these issues, will be broadcast across the state this week. Last week, he sent out a direct-mail appeal to contributors to raise $185,000 to finance the ads.

The purpose, say Coleman strategists, is finally to draw some sharp distinctions on important issues between their man and Robb, something they concede they have not been able to do through most of the campaign. The result, they hope, will be to fracture the remarkable coalition of traditional Democrats and conservative independents that Robb has put together.

Reagan's long-awaited appearance Tuesday could be worth up to three points to Coleman on election day, the Robb camp concedes. Robb's people hope to blunt the presidential appearance by negative ads that will continue to portray Coleman as a political opportunist of low credibility whose record doesn't qualify him to carry the conservative banner or sit in the Governor's Mansion.

"If it's a referendum on Reagan, then he Coleman wins," said Robb in an interview today, adding that he thinks the race, instead, "will boil down to . . . who the people feel most comfortable with."

The Reagan cloud could have a silver lining for Robb, whose polls suggest a large 20 percent of the state's traditionally Democratic black vote still is undecided. Doak and other strategists are counting on Reagan's visit to help "bring home" those voters to Robb.

One wild card, both campaign organizations agree, is the conflict of interest allegations against Coleman's lieutenant governor candidate, state Sen. Nathan H. Miller. Robb began a series of hard-hitting radio spots two days ago, charging that Coleman was "caught in a web of scandal." Some Republicans predict that the spots, coupled with a clumsy effort by Democrats in the state senate to hold a public hearing on the allegations last Friday, could backfire and produce a sympathy backlash for Miller.

Doak said that the Robb campaign has continued its negative media attack on Coleman because, "every time we get off negative and they continue it, our polls show they've gained ground." He added that the media spots were necessary to counter the GOP's direct-mail blitz, which is expected to hit voters later this week.