In Virginia, the 1988 Senate race is evolving as a tense waiting game, with some Democrats eagerly hoping that former governor Charles S. Robb will challenge freshman Republican Sen. Paul S. Trible Jr. -- a move that polls indicate would tip the scales in favor of the Democrats.

But next door in Maryland, where two-term Democratic Sen. Paul S. Sarbanes increasingly looms invincible, some Republicans are questioning whether they can field a challenger.

Dan Fleming, the Maryland Republican chairman, recently circulated a letter trying to spark interest in drafting U.S. Education Secretary William J. Bennett to challenge Sarbanes until it was learned that Bennett is registered to vote in North Carolina and has no interest in running.

Jeane J. Kirkpatrick, the former U.S. ambassador to the United Nations, previously added her name to the growing list of prominent Maryland Republicans who decline to seek the Senate seat. The latest rumor within candidate-starved Republican circles is that Tom Clancy, author of the best-selling "Patriot Games" and "Red Storm Rising," is pondering a bid.

"I'm constantly hearing there's going to be a candidate emerging any day," said Del. Ellen R. Sauerbrey (R-Baltimore County), the House minority leader. "But the candidate is an elusive person."

The fund-raising efforts of the incumbents, meanwhile, reflect the distinctly different political situations they face, according to reports filed recently with the Federal Election Commission.

Sarbanes, a liberal Democrat who weathered a well-financed media attack from the National Conservative Political Action Committee (NCPAC) in 1982, has raised $406,565 for next year's campaign. More than a third of the funds were contributed by political action committees, and the remainder were in the form of individual contributions, many coming from out of state. Six years ago, Sarbanes had raised only $78,000 at this point in his campaign.

Sarbanes plans to hold several fund-raising events this fall, with the goal of raising close to $1 million by the end of the year, according to an aide. But clearly he is under far less pressure than Trible to sock away funds.

Trible, a conservative Republican, has raised $1.6 million -- an impressive war chest for so early in the political season -- in hopes of warding off a serious Democratic challenge. As of June 30, the close of the latest reporting period, Trible had $1.4 million in cash on hand. He, too, has received more than a third of his funds from PACs.

According to a survey conducted July 23-26 by Mason-Dixon Opinion Research, Virginia voters would favor Robb over Trible, 52 percent to 37 percent, in a race for the Senate, with the rest undecided. Without ruling himself out, Robb this year urged millionaire Ronald I. Dozoretz, a Virginia Beach psychiatrist and vice chairman of the state Democratic Party, to get in the race. Since then, the Dozoretz boomlet has fizzled, and Robb supporters say they are increasingly optimistic that Robb will take on Trible.

"I think he {Robb} is looking at the position from a positive standpoint this time," Virginia state Del. Alson H. Smith Jr. (D-Winchester), the former governor's longtime ally and fund-raiser, said last week.

The Washington Post reported in February that Robb, currently a lawyer with the firm of Hunton & Williams, was strongly considering a race for the Senate, largely out of concern that his stock as a public figure would dwindle in a prolonged period without holding public office. Robb was governor from 1981 to 1985.

His supporters contend that, unlike other Democrats pondering the race, the highly popular Robb can afford to wait until late this year before reaching a decision and still have time to raise the necessary funds to mount a successful statewide campaign. Democratic Reps. Norman Sisisky of the 4th District and Frederick C. (Rick) Boucher of the 9th District are also considering entering the race.

"The amount of money Paul Trible has raised or will raise has nothing to do with Gov. Robb's decision," said Smith, who likely would play a major role in fund-raising for the former governor.

Sarbanes, a member of the Foreign Relations Committee and chairman of the Joint Economic Committee, would be extremely difficult to unseat, Democrats and Republicans agree, particularly in a state where Democrats hold a better than 2-to-1 edge in voter registration. Sarbanes whipped Republican Lawrence J. Hogan, a former House member and Prince George's County executive, in 1982 with 63 percent of the vote. Last year's landslide Democratic victories by Maryland Gov. William Donald Schaefer and Sen. Barbara A. Mikulski underscore the Republicans' problems in mounting a statewide campaign.

Fleming said last week that a couple of "high-powered" Republicans are giving serious thought to entering the Senate race and will reach decisions by October. "We do expect to put up a substantial challenge to Sen. Sarbanes," he said. But other Republicans say the prospects of recruiting a top-flight challenger are bleak.

"I'm not aware of anyone who is going to run against Sarbanes," said Maryland state Sen. John N. Bambacus (R-Frostburg). " . . . It would be difficult for anyone in the party, short of an Ollie North, to run against him."

Sarbanes and Trible, to varying degrees, have capitalized on their appointments to the Senate select committee investigating the Iran-contra affair, although Virginia Democrats argue that Trible "wimped out" in his questioning of Marine Lt. Col. Oliver L. North.

The appointments catapulted the two senators into the thick of the most important and widely reported congressional investigation since Watergate and enhanced their standing in the Senate.

Trible, a former prosecutor and House member, initially came on strong, winning kudos from his committee colleagues, the news media and even some Virginia Democrats for displaying an independent streak.

He criticized the White House for arrogantly disregarding the concerns of Congress and for "privatizing" foreign policy. He blasted Richard V. Secord, a retired Air Force major general, and Secord's partner, Albert A. Hakim, as "out-and-out profiteers" for their roles in the sale of arms to Iran and supplying the contras. Trible described North, a central figure in the affair, as a man "who lives in a world somewhere between reality and fantasy."

But Trible noticeably toned down his rhetoric and the intensity of his questioning during North's highly celebrated testimony in July. By then, Trible had come under pressure from conservative Virginia Republicans who were displeased with his conduct in the hearings. Trible -- one of four senators and House members designated to lead the questioning -- heaped praise on North and sought to shift most of the blame to Secord and Hakim.

"You've captured the imagination of the American people," Trible told North, "and you've done that, I think, because you told the truth, fully and candidly, because you're a man who was obviously doing his duty as he saw it, because you were acting with the knowledge and authority of your superiors."

Virginia Democrats howled that Trible had backed down under pressure and had passed up a golden opportunity to achieve significant stature as a senator.

"This is somebody who talked tough until it was time to produce," said Lawrence Framme III, chairman of the Virginia Democratic Party. "Then he stuck his finger in the air, saw which way the political winds were blowing, and acted accordingly. It was government by windsock."

But Trible's supporters say his performance was a political plus, overall. The Mason-Dixon poll, conducted shortly after the hearings, showed that 59 percent of those interviewed gave Trible high marks for his performance in the hearings.

Richard Cullen, a Richmond attorney who served as Trible's legislative aide during the hearings, said that Trible's questioning of North illustrated that at the same time the Nicaraguan contras were fighting with inadequate weapons and supplies, Secord and Hakim had secretly siphoned off millions in profits from the illegal arms sales.

"If Trible had attacked North, he would have been less likely to respond to the key questions in the manner in which North did," Cullen said. " . . . The questions were probing and hard. He {Trible} asked good questions, and there's nothing to apologize for."

Trible was unavailable for comment.

Sarbanes approached the Iran-contra hearings in his typically low-key, methodical style. But he finished strong, many agree, sharply criticizing President Reagan for knowingly or unwittingly allowing a "junta in the White House" to ignore congressional mandates and short-circuit the democratic process.

"I think no matter how you resolve the factual discrepancies, there is no scenario that is a positive one for the president," Sarbanes said in an interview.

In contrast to Trible, Sarbanes lectured North during the hearings for allowing his zeal in providing aid to the anti-Sandinista forces in Nicaragua to warp his judgment.

"If we have a system where policymakers are seeking to implement their views regardless of the decisions that have been made constitutionally, then we're undermining the integrity of the political process," Sarbanes said.

Peter Marudas, Sarbanes' top political adviser, said the hearings were useful in showing off the style and substance of a senator who normally shuns the limelight -- one who has been portrayed by his critics as overly cautious and reluctant to get out in front of important legislation.

"People in the state and elsewhere got to see him at work," Marudas said. "We think if people see the senator working, they see what a good senator he is. He's thoughtful, he's responsible, he has respect for the integrity of the {government} process.

"Some people, in the conventional sense, see his image as fuzzy, but you have to start from the premise that people view him positively," Marudas said.