In recent issues of his biweekly newsletter, The American Political Report, and in an article in last Sunday's New York Times Magazine, Kevin Phillips has offered as interesting an analysis of the Reagan administration and its political prospects as anything that has come across this desk.

Phillips writes from the perspective of a conservative who shares many -- if not all -- of Reagan's policy goals. He has been not just a student but a proponent of the conservative movement since his late-1960s book, "The Emerging Republican Majority," written after a stint in the Nixon administration.

This background is part of what makes Phillips' views so interesting today. Many -- including me -- are far more dubious of some of Reagan's policies. But we have written of his election and reelection as signaling the advent of a possible conservative era in national affairs. Phillips has been moving in the other direction.

He argues that 1984 is likely to be seen as the high-water mark of conservatism in this current political era, and that the tide of sentiment and elections is far more likely to swing back in the other direction.

In his newsletter, he has argued mainly that economic and political cycles are conspiring to frustrate the conservatives' hopes. In the Times piece, he added a third factor: the human "overambition" and exaggerated pride or "hubris," which, he says, is leading the Reagan administration to misinterpret and overstate the mandate of his reelection.

Phillips is the popularizer of the notion of the "six-year itch." He has drawn attention to the pattern of severe off-year losses of Senate, House and gubernatorial seats for the president's party in the sixth year after a change of party control of the White House.

What happened to the Republicans in 1958 and 1974 (six years after Eisenhower and Nixon were first elected), and what happened to the Democrats in 1938 and 1966 (six years after Roosevelt and Kennedy won), is likely to happen to the GOP in 1986, he said: a political bath.

The political cycle, he argued, is linked to an economic cycle of severe recession or inflation occurring at that point of a party's tenure in the White House.

As many of the rest of us have watched the changing candidate picture for 1986, we have written about the improving odds for continued GOP control of the Senate and for gubernatorial gains. We have seen Reagan's agreement to the Senate budget package as the possible harbinger of sustained economic growth. And we have suggested that tax reform is an issue on which Republicans may lock in the allegiance of previous ticket-splitters and Democrats.

But through all this, the conservative pessimist Phillips has been plucking at our coats and warning, "Do not disregard the patterns of the past."

Now, in the Times, he has added another argument. "Mandate hubris has helped nurture excesses" in the second-term Reagan White House, ranging from interventionism in Nicaragua to cutbacks in Social Security and other middle-class entitlement programs, to laissez-faire tolerance of trade deficits, to continuing emphasis on "fundamentalist religious goals."

Is Phillips right? Is Reagan in the process of blowing the conservatives' big chance? There is a contradiction inherent in his argument. If the cycles of party growth and decline are as ironclad as he suggests in his "six-year itch" theory, then Reagan is powerless to avert a Republican debacle in 1986 and probably in 1988, and his policies are irrelevant.

But I doubt the automaticity of those cycles. A party that can reduce the deficits and tax rates (via tax reform) in its second term, as Republicans may be able to do, can perhaps sustain economic growth and earn enormous political credit.

Such a performance could well outweigh voters' doubts about elements of that party's foreign and social policies.

Still, I think Phillips is right -- and enormously relevant -- in reminding us that all of American history suggests we will see swings in public mood from wanting governmental activism to fearing it, and back again.

To the extent that Reagan has identified conservatism with outright opposition to any governmental initiatives unrelated to national security, he has almost certainly limited its long- term tenure in power.

Phillips is wise in reminding his fellow conservatives in power that people want more from government than stockpiles of missiles. As he wrote, the threats of "America's jeopardized agriculture, eroded manufacturing competitiveness, run-down transportation infrastructure, shaky financial institutions and troubled educational system may be about to force Washington's hand." When they do, the voters may turn from Reagan's anti- government rhetoric to the Democrats for activist responses.

As the old saying goes, "What goes around, comes around."