Activists of both major political parties tried to wrap themselves in the populist mantle yesterday at a day-long conference aimed at exploring the populist tradition and debating which party will be able to lay claim to it.

"We're all huntin' the same animal but with different dogs," Texas Agriculture Commissioner Jim Hightower said.

Hightower, a founder of the New Populist Forum and an unabashedly liberal Democrat, was on a panel that discussed "The New Populism: Progressive, Conservative, Republican, Democrat, Other?"

His fellow panelists were another Forum founder, Sen. Tom Harkin (D-Iowa); Rep. Newt Gingrich (R-Ga.) and Deputy Treasury Secretary Richard G. Darman.

All agreed with Hightower that "populism doesn't belong to anyone in this room or on this panel; it belongs to the people."

The debate, however, was over which party and which ideology, liberal or conservative, would offer the brand of populism that people will buy.

Earlier, political analyst William Schneider of the American Enterprise Institute had argued that "since the New Deal, Democrats have laid claim to economic populism, while since the civil rights movement Republicans have moved to social and cultural populism."

Democrats are economic populists but cultural elitists, while Republicans are the opposite, he said.

"In the New Deal, government was anti-elitist but, by the 1970s, it was like William Jennings Bryan's definition of big business as 'nothing but a collection of organized appetites,' " he said.

Darman described populism as an ill-defined movement that included people with high but frustrated expectations and individualists with class resentments whose dominant concern is for fairness and opposition to elitism and the concentration of power.

"It's a corrective force, not an ideology, and it has both negative and positive aspects," he said. "Negativism is a reactive resentment of abuses, positivism is creative programs to correct them. Populism today is a negative reaction to government and the positive creation of this administration of a society of opportunity."

The populism of the 1970s -- of George McGovern and Jimmy Carter -- was aimed at abuses by the private sector, whereas today its concern is big government, Darman said.

Hightower and Harkin disagreed.

"Fundamentally, populism addresses the problem that too few people have too much money and power, which is the same old struggle of the old populism," Hightower said.

"It doesn't seek a liberal solution, to give welfare to the farmer who's been forced off his land, or a conservative solution, which is to say, 'I got mine, so long, sucker.' The idea is to put the tools of self-help in people's hands, to free up their enterprise so that prosperity doesn't trickle down, it percolates up," he said.

Harkin denounced the Reagan administration as "government working as a branch of the Chase Manhattan Bank. . . and run by managers from the Heritage Foundation."

He described the $2 trillion national debt as the result of "the most antipopulist policies ever, a massive transfer of wealth up to the rich -- and out of the country."

Gingrich described populism as "a special effort by individuals or regions to get access to the American dream that they've been deprived of."

He predicted that conservative populism will dominate because "traditional life styles always defeat radical life styles" and populism "doesn't just go to the bank and pocketbook but to life styles and value systems."