They are out-Reaganing Reagan. As the Republican platform committee winds up its drafting work, its conservative members have done more than just put their stamp on the document to be presented to the GOP convention next week. In some areas, they have nudged it farther to the right than the administration would have liked - not because Mr. Reagan personally opposes the ideological stand but because it is more politically advantageous to occupy the center ground in an election year.
The platform committee, dominated by young House conservatives, has supported planks that:
* Strongly oppose any tax increases to balance the budget. The President has said he would turn to tax hikes only ''as a last resort.''
* Call for a move to reduce taxes on interest income and criticizing graduated tax rates.
* Advocate elimination of the windfall profits tax on domestic oil.
* Favor abolition of the Department of Energy (which the President has backed away from).
* Plug the gold standard as a ''useful mechanism'' to foster price stability.
* Assail the ''destabilizing actions'' of the Federal Reserve Board's tight monetary policy.
Under pressure from the White House, the platform committee has softened some language. Former Transportation Secretary Drew Lewis, the White House liaison with the committee, said the administration is ''totally satisfied'' with the planks on fiscal issues. But he also stated that ''this is not a declaration of victory.''
Earlier this week, platform subcommittees voted on other conservative planks on social and foreign-policy issues. These were under consideration by the full committee yesterday and included strong antiabortion statements, such as support for the appointment of judges who ''respect traditional family values and the sanctity of innocent human life.''
Moderate Republicans on the 106-member committee, who are in the minority, voice disappointment and frustration over both the content of some of the planks and the drafting process itself.
''We didn't even get the document until after the Monday hearing, so we couldn't give it adequate attention,'' says Connecticut state Rep. Julie D. Belaga.
Critical of the fact that the platform committee did not hold regional hearings on the platform, moderates feel that the conservatives have railroaded the platform through.
''The national party is a very conservative party now, and the platform committee reflects the national organization, the White House, and the state leadership,'' says Sen. Lowell P. Weicker Jr., also of Connecticut. ''But it does not necessarily reflect the Republican rank and file. Many Republicans will support Ronald Reagan but not the platform.''
While Mr. Reagan did not get the ''wiggle room'' on tax increases he would have liked, his lieutenants did manage to obtain compromise language on the issue of a flat tax. The original draft called for ''complete tax reform'' through a flat tax system. The plank adopted by the full committee says simply that a ''modified flat tax ... is a most promising approach'' to a fair and simple tax system.
White House strategists, concerned about giving the Democrats ammunition on the issues of budget deficits and favoritism of the rich, also successfully stopped a move to extend Individual Retirement Accounts to all family members, including children. There was heated debate on this question, with supply-side advocate Sen. Bob Kasten of Wisconsin arguing that families should be able to set up IRAs to pay for college education or to help their children buy their first home.
Traditional fiscal conservatives won out; the draft platform now calls for extending IRAs only to homemakers, a proposal also favored by Democrats.
In the battle over the platform, Reagan strategists have been careful not to push too hard, wanting to avoid alienating the President's staunchest supporters or contributing to the appearance of party divisiveness. ''If you look at most of the issues that we're dealing with, rather than try to eliminate those issues we were uncomfortable with, we tried to make the language permissible rather than mandatory,'' Mr. Lewis said.
Nonetheless, the platform proceedings this week indicate that the Republican Party, although it is united in its support of President Reagan, contains divergent points of view and some intense rivalries.
The Democrats are expected to target the GOP platform in their continuing attack on Reagan's tax intentions. Platform writers this week gave the President less maneuverability than he sought by inserting the comma in the following passage:
''We therefore oppose any attempts to increase taxes, which would harm the recovery and reverse the trend to restoring control of the economy to individual Americans.'' Without the comma, the platform's opposition to tax hikes would have been contingent on whether the economic recovery was being impaired. With it, the opposition is absolute.
The platform also states that the party foresees ''no economic circumstances which would call for increased taxation.''
Lewis has made clear, however, that while the GOP platform is a policy statement for the Reagan candidacy, ''there's no way we as a Republican Party can take away the prerogatives of his office.''
In short, there's still room to ''wiggle.''