Does Hoover rank among great statesmen?

As Republicans wind down their national convention in Dallas this week with the renomination of Ronald Reagan, there's a lingering political ghost in their midst which they would once and for all like to exorcise: Herbert Hoover.

One of the nation's most maligned Presidents, Hoover - more than 50 years after his four-year stint in the Oval Office - still carries the label as the father of the Great Depression of 1929. He is lampooned in song and verse. Democrats point to him as the epitome of the evils of the GOP. And Republicans, for the most part, choose to ignore him.

His current biographer, however, says it's time to rehabilitate Hoover, honor him for his broad contributions to the nation, and purge the ghost of its ghostliness.

In fact, in ''An Uncommon Man: The Triumph of Herbert Hoover'' (Simon & Schuster), Richard Norton Smith argues that the stardom of President Reagan today may well have been presaged by Hoover's ''staying the course on conservative politics a half century ago.''

But Smith would be the first to admit that it's about as likely that Reagan campaign brain trusts will embrace Herbert Hoover as they would sing the praises of a Watergate-burdened Richard Nixon. In a Monitor interview, the biographer discussed the role of Hoover in American politics, ranked him suprisingly high among US leaders, and compared his brand of conservatism with that of the present occupant of the Oval Office.

A self-made man, a brilliant mining engineer, an acknowledged genius as an administrator, Hoover was seen by many of his contemporary politicians - Republicans and Democrats alike - as the man best fitted for the presidency. Even Franklin D. Roosevelt, who defeated Hoover in the incumbent's bid for reelection in 1932, had earlier heralded the Iowa Quaker's Oval Office potential. Democrat Woodrow Wilson was also once a strong Hoover booster for the White House.

Hoover's successful climb from humble rural roots, his phenomenal business success, his academic brilliance, his leadership ability, his concern for the less fortunate, his candor, his decency, his extreme honesty, seemed to make him a natural for the nation's highest office.

What happened? Smith states the obvious: the depression. But poor relations with Congress, inability to communicate with the public and press, and often bungling and wrongheaded assessments of national interests added to the problems of the Hoover presidency.

There were important presidential accomplishments: Hoover added 2 million acres to the national parks; he focused government attention on the need to provide care and protection of children; he championed a graduated tax system to favor lower-income Americans. But these quickly faded in the public memory. Instead, the nation made Hoover the main scapegoat for the economic crisis. Shantytowns, ''Hoover Blankets,'' and ''Hoover Pullmans'' became the mark of a man who had once been been the pioneer of worldwide food relief programs and honored for his humanitarian efforts on behalf of the less fortunate.

''Here was this great local hero who was the most admired American in the world (and) then became the most hated American in his own country,'' Smith explains.

Despite the overwhelming setbacks, Smith insists that history will someday record Hoover ''among the few 'greats' as a man, even though his service in the presidency would have to be ranked as ''in the middle of the crowd.''

Smith's thesis is that the four years in the White House are merely a ''footnote'' to Hoover's extraordinary career. ''If you accept that and look at the larger career..., I have a theory that Hoover was maybe among the two or three greatest men ever to be President,'' he says. Though not a great President , he had the ''intellectual depth, dimension, and character,'' to rank with ''a Jefferson or Lincoln.''

Smith stresses Hoover's ''character'' as his shining quality. He points to a recent Chicago Tribune poll that ranked US Presidents in such areas as congressional relations, personal character, and leadership ability. He says Hoover was in ''the top two or three'' in terms of ''character'' - but average in other areas. (The public ranked Nixon at the bottom in the ''character'' category.)

How might Hoover have assessed Ronald Reagan's presidency?

Smith believes that the former President might generally applaud Reagan's conservative fiscal policies. ''But he would be aghast at (an almost) $200 billion deficit..., and he might have been very wary about a lot of Reagan's foreign policy,'' the biographer says.

Further, Hoover would have had serious reservations about what ''passes for conservatism'' today, Smith adds. ''He was a (type of) fundamentalist. But (he might have thought that) fundamentalists don't belong in politics, certainly not in pluralistic, bureaucratic democracies.''

Smith tabs Hoover an ''odd Quaker'' in terms of his thinking on foreign policy. ''In the 1950s, he was adamant that the US should not get involved in Indochina in a land war in any way. He said it would be the death knell of the Republican Party.... However, when the Bay of Pigs took place, he said that (President John F.) Kennedy should have sent in more troops and wiped out the Cubans.''

The Smith book focuses on Hoover's post-presidential years, particularly his service to Presidents Truman and Eisenhower - his work on a worldwide mission to feed the hungry and on two commissions dedicated to reorganizing the government. The biographer insists that Hoover probably outranks any former President in his post-White House contributions to the nation.

A good final argument can be made, says Smith, that Hoover may have been ''wrong in terms of geopolitics but terribly right in terms of Christian values.''