Ten years after the inauguration of Ronald Reagan and the GOP takeover of the Senate stirred their dreams of a new political order, Republican Party officials gather here today with a nagging sense of unfulfilled expectations.

While a Republican is still in the White House, a 10-year investment of $1.2 billion by the three major GOP campaign committees has failed to move the party beyond that beachhead. Democrats have a substantially stronger hold on the House, have regained control of the Senate and retain a decisive advantage in the nation's state legislatures.

"We haven't lost what we gained during the Reagan years," said Frederick Steeper, a Republican pollster. "We were 15 to 20 points back {in terms of voter identification with the two parties at the start of the 1980s}, Reagan brought us to parity and we still are at parity."

"But," he added, "there hasn't been any sign that we are making further gains, and we need to. There is always hope, but I don't know what is going to break that {Democratic control of the House and the legislatures} loose."

His frustration is shared by many who will be attending the Republican National Committee's semi-annual meeting to confirm President Bush's choice of Agriculture Secretary Clayton Yeutter as party chairman. "We won the foreign policy and defense struggle, we are winning the cultural war, and we have been losing the political war," said House Minority Whip Newt Gingrich (R-Ga.), who nearly lost his own seat in Congress last November.

The GOP, said Gary C. Jacobson, a political scientist at the University of California at San Diego, "should have done better. They can't argue that the money was well spent. Simply looking at the level of success, considering the size of the {Republican} organizations and their financing, they have to be terribly disappointed."

Jacobson said his own studies show that initially the GOP had an advantage in both recruiting better candidates and in channeling cash from party and private sources to challengers and open seat candidates, but by the end of the decade, the Democrats had taken over the advantage in both of these key areas.

Sen. Phil Gramm of Texas, chairman of the National Republican Senatorial Committee, believes, like Gingrich, that a major reason for the party's lack of success is its inability to engage Democrats directly over ideological issues. The Democrats' success, he said, is based on its ability to avoid these confrontations rather than any advantage in fund-raising.

Gramm said his own polls show that voters in Texas want members of the House "to get things for Texas, rather than being national leaders," and the Democrats have succeeded in keeping the issues in congressional elections favorable by "making all politics local."

Looking at the repeated success of Republican presidential candidates, Gramm argues that "the good news is there is a majority out there waiting to be formed, the bad news is we have not presented them with a clear enough vision that it has coalesced."

His strategy to achieve such a presentation of Republican vision in House and Senate contests is to encourage repeated congressional votes that show "where we stand on crime and punishment, on {racial} quotas, and on the size, scope and power of government," attempting, in effect, to translate the issues that often drive presidential contests into lower level battles.

Along with the general agreement that the Democratic Party has more than held its own through the past decade, elected officials and strategists of both parties agree that there are a number of other trends sure to influence the strength of each party in the coming years, some favorable to the GOP, others unfavorable. These include:

The Republican Party's substantial advantage among young voters. Among these voters, turnout is low, and the GOP tilt has not yet translated into major gains in House and Senate elections, but may become more influential in the 1990s as the voters reach their 30s and vote in higher percentages.

"Demographically, if you look at the voting patterns of young people, they now find reason to be Republican," said Gramm, a convert himself from the Democratic Party. "I think that is the strongest force out there, but it has not been effectively mobilized."

"One of the most fascinating things to watch will be the young voters," said Democratic pollster Paul Maslin. They "are more patriotic, more willing to use force, more willing to see American strength being projected" -- all tendencies that suggest President Bush's decision to go to war with Iraq may reinforce GOP loyalties.

But, Maslin said, they "are the ones most touched by the actual reality of war, whether themselves or their cousins. . . . and this is not just a Rambo war now, this is a real war now."

The GOP's gradual loss of its traditional advantage in fund-raising. According to the most recent information available from the Federal Election Commission, the flow of cash to the three conduits of party funds -- the national, congressional and senatorial campaign committees -- has declined steadily, while the Democrats, still far behind, have held their own.

A number of Republicans attribute the fall-off to Bush's inability to build and maintain support among conservatives.

"Bush manipulates the symbols of the value differences {between Democrats and Republicans} less well than Reagan," said one GOP operative who did not want to be quoted by name. Another Republican added that Bush's abandonment of the "no new taxes" pledge was "a fund-raising disaster."

The GOP's strong and continuing advantage -- acknowledged by Democrats -- in the competition for the presidency.

"Over the last four or five years, the momentum behind the Republican Party is beginning to disappear," said Walter F. Mondale, the 1984 Democratic nominee. But, he said, "I think we are still in deep trouble at the presidential level. They {the GOP} seem to be the American presidential party."

Rep. Robert G. Torricelli (N.J.), an intensely partisan Democrat, warns that the presidential prospects of his party were harmed by the Democratic majority that voted against granting Bush authority to go to war with Iraq.

Historically, the Democratic Party has backed a foreign policy based on the use of international law and the use of the United Nations. "It is an irony of history that this vision may be fulfilled by the current efforts of George Bush {in the Persian Gulf} . . . while Democrats are adopting some of the isolationist tendencies previously associated with the Republican Party," Torricelli noted.

The GOP's ability to dominate the tax issue. Howard Baker, who served as majority leader during the brief period Republicans controlled the Senate, argued that on the issues of spending and taxes, "we are still on the Reagan course. Ronald Reagan will be remembered as a president who did what few do, changed the direction of public policy."

Possible challenges to Bush from the party's right wing. The administration will attempt to crush such a challenge at today's meeting when Morton Blackwell of Virginia will try to win approval for a resolution calling for the resignation of Budget Director Richard G. Darman.

On a broader scale, David Mason, director of executive branch liaison for the conservative Heritage Foundation, said the initial success in the "Persian Gulf conflict doesn't solve the problems we have in the domestic area."