"A talented politician and one of the House's ablest legislators" was how the authoritative "Almanac of American Politics" described Rep. Gillis Long, the Louisiana Democrat, who died this week at 61.

First elected to the House in 1962, Long lost his seat two years later after being accused by his conservative opponent of helping pass the Civil Rights Act by having voted, at the request of the Kennedy White House, to enlarge the House Rules Committee. Ten years passed before Gillis Long returned to Congress where he served so ably.

To its own disservice and eventual regret, Long's party in recent years chose to ignore his wise counsel that it was necessary for Democrats to demonstrate their "compassion to care, but also the toughness to govern." During and between recent campaigns, a lot of Democrats have seemed to emphasize compassion while simultaneously disdaining toughness.

One result of that decision will be that as of Jan. 20, 1989, the Republicans will have held the presidency for 16 of the last 20 years. As Gillis Long understood, American voters prefer their political leaders competent as well as compassionate.

Throughout the most recent presidential campaign, Democratic optimists were invariably encouraged by the public opinion surveys, which almost uniformly showed the electorate's judgment that the Democratic candidate was more concerned with their personal well-being than was the Republican incumbent. One Washington Post/ABC News survey indicated that, by nearly a 2-to-1 margin, voters judged that Ronald Reagan sided "with special interests" rather than "with the average person." In the same survey, voters by a margin of 3 to 2 saw Waltr Mondale on the side of "the average person."

In poll after poll, voters said that Democrat Mondale did "care more" about people like themelves, more about the elderly, more about the less fortunate and more about an arms limitation agreement with the Soviets. And, yes, said these very same voters, they were going to vote for Ronald Reagan, something they did do in record numbers.

But as political philosopher Alan Baron explains and Gillis Long understood, the logic of the voters is compelling. Consider Baron's analogy: In one hour, you are about to have 20 guests for an important dinner at your home. Your water pipe bursts. You have to make an immediate phone call. Now, who "cares more" about your about-to- be-ruined dinner and your predicament -- your dear Mom or your local plumber? And who knows more about the theory of water pressure -- the chairman of the local university's engineering department or the local plumber? Who has more personal charisma -- Robert Redford or the plumber?

Whom do you call? You call the person with demonstrated competence, even if he does not care as much about your personal happiness and emotional well-being.

In a number of recent national elections, voters have understood that the Democrats have been more genuinely concerned with their happiness and more genuinely compassionate about the less fortunate than their opponents. But the opponents seemed to be much more likely to be able to fix the busted pipes before the evening was ruined, or worse.

Caring is a large help in winning congressional races. Americans are compassionate people, and they appreciate that quality in their elected representatives. But in their presidents, in addition to that compassion, the voters want, as Gillis Long told his fellow Democats, "the toughness to govern" as well.