Republicans held their big straw poll in Ames, Iowa, in the shadow of an anniversary: Twenty-five years ago this month, Richard M. Nixon became the first and only president to resign. In light of every Republican's claim these days to be a true conservative, it's worth considering that Nixon was the last president of the liberal era.

How, you may ask, could the Nixon of the Southern Strategy, "positive polarization," the "silent majority," the House Un-American Activities Committee be associated with anything called liberal? As Al Smith said: Let's look at the record.

Didn't Nixon sign the Clean Air Act and laws creating the Environmental Protection Agency, and workers' safety protections? Didn't he approve indexing Social Security to inflation, lifting millions among the elderly out of poverty? Didn't he propose a guaranteed annual income for the poor?

In 1980 Ronald Reagan charged that America's defenses had weakened because the federal government was spending too little on defense as compared with social programs. The trend Reagan decried began under Richard Nixon.

As Michael Barone reported in his fine 1990 book "Our Country," a comparison between the 1968-69 budget of Lyndon Johnson and the 1971-72 budget of Richard Nixon reveals these spending changes: Social Security spending, up 55 percent; nondefense spending, up 44 percent; defense spending, down 3 percent (and that with a war on in Vietnam).

And what about Nixon's economic policies, including wage-price controls -- the ultimate intrusion of government into the private market? As Barone noted, Nixon's policies, crafted by his Treasury secretary, John Connally, "brought more state direction to economic policy and did more to undercut the operation of free economic markets than anything done, except in war, by the Roosevelt, Truman, Eisenhower, Kennedy or Johnson administrations."

Historian Joan Hoff in her 1994 book, "Nixon Reconsidered," wrote: "By and large, politics made Nixon more liberal than conservative in economic matters, confounding both his friends and enemies, as he also did on other issues of domestic reform, especially civil rights and welfare."

Oh, yes, there was that little opening to the country he once denounced as "Red China." And in 1971 Nixon proposed a national health insurance program that bore important similarities to the plan put forward 22 years later by one William Jefferson Clinton.

Now, liberal stomachs may turn at the idea of the Progressive Richard Nixon. Relax. One of the many paradoxes of the man is that he put a decidedly conservative twist on his liberal accomplishments.

Encouraged by the argument of Richard Scammon and Ben Wattenberg that social issues such as crime, race and traditional values were pushing working-class Democrats to the right, a young Nixon aide called Pat Buchanan persuaded his boss to run for reelection as a vociferous social conservative. Nixon did. He attacked school busing for integration, excoriated student radicals and flag burners, defended the "silent majority" of tax-paying, family-raising, law-abiding Americans.

And then came Watergate, a direct product of the politics of polarization that Nixon pursued.

The truth about Nixon is not that he was a liberal but that he was a pragmatist reacting to a political environment shaped by liberals. Many of the liberal initiatives he signed were pushed on him by a Democratic Congress.

As Emmet John Hughes, an Eisenhower speech writer, once said of Nixon: "The philosophy of any policy interested him, quite evidently, far less than its efficacy; he judged any declaration of speech not by its content but by its impact." Still, we live today with some of the achievements of Nixon's accommodationism, especially where the environment and the well-being of the elderly are concerned.

A final irony: The response to Watergate, and its anti-constitutional abuses of federal power, fed the very anti-government wave that Ronald Reagan rode to election in 1980. If the federal government was as corrupt as Nixon's opponents said it had become under his watch, how could liberals make a case for it as a fit vehicle for social improvement?

Robert Borosage, a leader of the liberal Campaign for America's Future, offers this parallel for our time: If Nixon was the last president of the liberal era, Bill Clinton may be the last president of a conservative era. Clinton, like Nixon, accommodated a political time shaped by his opponents. And Clinton arouses the same level of hatred among his foes as Nixon did.

There's wishful thinking in Borosage's metaphor. He may also underestimate how Clinton's presidency reshaped the political environment in a less conservative direction. But Borosage's view reflects a shrewd understanding of the ironies of history -- the very ironies Nixon mastered before he was engulfed.