Larry Sabato, the University of Virginia assistant professor who has become one of the state's most respected election analysts, has concluded that Republicans continue to win in Virginia because they have won the battle for the suburban heart and mind.

In his analysis of the recent U.S. Senate election, published and copyrighted in the Richmond Times-Dispatch, Sabato points out that Republican John W. Warner ran up a majority of 54.1 percent in the conservative suburbs that was just enough to overcome Democrat Andrew P. Miller's performance in the rest of the state.

According to Sabato's figures, Miller, buoyed by a typically overwhelming Democratic vote of 94 percent among black Virginians, clobbered Warner in central cities with a majority of almost 56 percent and won by a comfortable, three-point margin in rural areas.

These victories by Miller in the rest of the state, however, served in the end only to underscore the growing importance that Sabato accords to the suburban vote.

In 10 years of tracking Virginia election results, Sabato has perceived as clearly as anyone the importance of the growth of the suburban electorate. Between the 1969 election for governor and this year's Senate election, the total vote in fast-growing Virginia increased by one-third in non-presidential years and the suburban share of that vote rose from about 35 percent to about 40 percent.

The rise of Virginia Republicans to a place of ascendancy in statewide politics occurred simultaneously with the rapid increase in suburban voters. In four close elections during that period, Sabato points out, the Republican candidate carried Virginia solely on the strength of the suburban vote.

The four races were the 1972 and 1978 Senate elections, the 1973 gubernatorial election and the 1976 presidential election.

Of the dozen elections he referred to in his Warner Miller analysis, only in one did the Democratic candidate state carry the suburbs. Lt. Gov. Charles S. Robb got 51.1 percent of the suburban vote in 1977, a margin Sabato points out was a full 10 points below his majority in the central cities.

Although he did not elaborate the point in his commentary on the Senate race, Sabato's calculations of suburban voter turnouts bear out an important point he has made in interviews - namely, that a large turnouts in Virginia helps Republicans just as large turnouts nationwide generally help Democrats.

In national elections, Democrats like to see a large vote because it generally means that traditional Democratic voting blocs - black voters, labor, lower-income earners - are flocking to the polls. In Virginia, a large turnout indicates that the politically lethargic suburbanite is bestirred and voting Republican.

The two largest voter turnouts in this decade in Virginia were in the 1972 and 1976 presidential elections. In those elections, according to Sabato, suburban voters accounted for an even larger share of the total vote than they did in nonpresidential years. In 1972, the hugh suburban turnout for Richard M. Nixon benefited Republican Sen. William L. Scott in his upset of moderate Democrat William B. Spong.

Before the recent Senate election, Sabato correctly forecast a larger turnout than was expected by most campaign and party officials. He correctly assumed that suburbanites would provide the increase, but he incorrectly predicted that they would provide the Republican with a comfortable statewide margin.

Only after an official canvass by the State Board of Elections was Warner declared the winner by a margin of 4,721 votes out of 1.22 million cast - the closest general election for the Senate ever in Virginia.

In the end, Warner did not sell that well in all the suburbs, notably Northern Virginia. Miller carried Arlington and Alexandria handily, but those so-called suburbs have taken on many central city characteristics. More damaging to Warner and the Sabato projections was a slender Miller victory in Fairfax County.

Fairfax voters may have been influenced by Washington newspaper endorsements of Miller and by news coverage that focused on Warner blunders, especially misstatements about his political contributions to Nixon.

In the Richmond area, where newspapers strongly endorsed Warner, the conservative suburbs gave him a 30,000 vote margin. In Virginia Beach, the Hampton Roads suburb, Warner also rolled up a majority.

What are Democrats to do to woo the suburban vote? Sabato attributes suburban allegiance to the GOP to a "transfer of the symbols of conservatism" from the old Democratic Byrd Organization to the state Republican Party, but he does not prescribe a reversion by the Democrats to their stark conservatism of yesteryear.

The Republicans' conservative image was the main reason that newcomer Warner won, Sabato says, but he believes a hard turn to the right by Democrats now would risk loss of essential black, labor and liberal support.

Instead, Sabato counsels Democrats to submerge their factional differences, close the "technological gap" between their weak party organization and the well-oiled Republicans' and choose well-heeled candidates with personal styles that appeal to suburban voters.

He described the ideal nominees as "urbane, 'sophisticated,' photogenic, pleasant and soothing candidates who, possessed of the right skills and image, can be moderate-liberal without alarming conservatives and suburbanites."

He acknowledged that none of these things would be easy to do.