Linwood Holton, the first Republican governor of Virginia in this century, the candidate that Democrats appear to fear the most as a U.S. Senate opponent, leaned back, campaign weary, in his Arlington political office recently and mused over another grueling day of campaigning for the GOP nomination.

Holton had arisen early in Lynchburg that morning after a later night meeting with delegates to the June 2 and 3 state convention. He had driven a borrowed car in a snowstorm to Belle Haven Country Club south of Alexandria to meet prospective delegate from Fairfax County. He was making as many phone calls as he could during the afternoon to political advisers around the state. He would finish the night about 11 p.m. at a meeting of the Reston Republican Club.

"I guess I'm getting my just rewards for creating two-party competition in this state," he said.

It is a rigorous regimen that Holton must follow in his pursuit of the Senate nomination against three opponents, two of them considered with himself to be strong contenders. He seemingly has a right to be bemused by it all.

While a still-popular former governor often times could expect to easily win a party nomination for a Senate race, Holton is engaged in a tough fight whose outcome is by no means certain.

Holton does not have to turn back far to remember how easy it once was to pick up a Republican nomination. After waging a strong campaign for governor in 1965, he not only was unopposed for the nomination in 1969, but was able to set the date of the party nominating convention in the spring so that the GOP could get an early start on the general election campaign.

Even after his victory in 1969, candidates did not scramble for Republican nominations. Sen. William L. Scott, who is opening up the Virginia Senate seat by retiring after one six-year term, had the nomination for the asking in 1972 in what was considered a hopeless race against former Democrat senator William B. Spong.

But this year, a year in which all the GOP candidates and top party officials presume the Republican nominee will be the favorite in the general election, Holton finds himself scrambling to beat former national GOP co-chairman Richard D. Obenshain and former Navy secretary John Warner. He also is opposed by state Sen. Nathan H. Miller of Rockingham County.

Three days before he announced for the nomination, Holton saw himself as a possible first ballot victor with Obenshain second and Warner a distant third.

Now he considers Warner to be a serious threat but insists that he still will win 40 to 50 per cent of the delegates on the first ballot with Obenshain and Warner dividing the rest.

This is a crucial week for Holton. He has failed to dominate any of the early Republican city and county caucuses held to select delegates and must, in the opinion of campaign and party officials, make a strong showing soon.

Fairfax Republicans selected about 1,800 delegates Tuesday night to cast 371 of the convention's 3,081 votes - each delegate may cast as little as one-fifth of a vote - and Holton, now a resident of McLean, is counting on a good showing in his own county. However, since delegates need not commit themselves to a candidate, it may be weeks before it is known who has the advantage in the huge Fairfax delegation.

Holton said he also must end this week by winning a large majority of the Norfolk delegation - allotted 98 votes - to offset early Obenshain and Warner successes. Obenshain locked up 105 votes in Chesterfield County, a Richmond suburb, Monday night and was expected to have the upper hand in the contest for votes at the Richmond city convention last night.

That Holton must strive for his party's nomination puzzles Democrats who fear him because of his proven popularity with two of their traditional voting blocs, black Virginians and labor. Virginia election analyst Larry Sabato estimated that Holton won 37 per cent of the black vote in 1969, the best showing of any modern Republican candidate in the state.

In his courtship of Republican delegates, Holton makes his electability claims deftly by citing a poll at the end of his term as governor giving him a 77 per cent approval rating and by suggesting that endorsements from black voter organizations are likely if he is the nominee.

However, he is clearly aware that he has an image of being to the left of Virginia Republican regulars who will dominate the convention. He counters that image with tough, conservative talk on the issues.

At Reston, he said:

Of the Panama Canal treaties - "I would vote against (those treaties) because they have created the image of making the U.S. submit to extortion, even blackmail."

Of Sen. Edward M. Kennedy's national health proposals - "One thing coming up is the Kennedy bill to socialize medicine. You can call that hyperbole if you want, but it puts the medical profession under a federal bureaucracy that will pay the bills. I call that socialized medicine."

On a major federal tax reduction, strongly advocated by Obenshain - "Dick Obenshain brough that into this campaign and I think it is a good suggestion. However, we must go beyond a mere reduction in rates to eliminate taxes on capital gains and phase out taxes on corporate dividends that produce double taxation of profits."

On energy pricing - "I would let the market place take care of energy prices and expect the energy companies to put the profits into the search and development of new energy sources. You can always resort to an excess profits tax if necessary."

On nuclear power - "It is incredible to me that Jimmy Carter is running away from this technology apparently because of some people on the extreme edge of the environmental movement. I am not myself afraid of nuclear generation. I am happy that Vepco (the Virginia Electric and Power Co.) has taken the lead in this area. It is comforting to me to know that half of its generation will soon come from nuclear power."

On full representation in Congress for the District of Columbia - "I'm not prepared to make a new state of the District of Columbia." He was interrupted by cheers. "I am prepared to see representation in (the House of Representatives) but I am not prepared to see the dilution of direct representation of the states in the U.S. Senate."

Throughout his pitch to delegates, the easy style that made Holton a campaign virtuoso in the 1960s comes through as do the folksy stories. Dismissing Carter's tax deduction attack on the "three-martini lunch" as "petty," Holton said:

"I told some folks the other night that I cannot ever remember having a three-martini lunch, and one of them shot right back at me. 'It's hard to do.'"