In popular lore, as rendered by a host of advise-and-consent novels, TV miniseries and dreadful docudramas, Washington is a place riven with tensions created by the agonies of power and the awful burden of making fateful decisions. Most of these portrayals are false. Supposed great debates are seldom memorable and rarely eloquent. The political process is far more mundane than electrifying. Profiles in courage exist more in the mind of the politician striking a heroic stance than in the actual performance of the public servant rendering historic, difficult judgment.

Let it be recorded, though, that yesterday the reality of political Washington lived up to its fictional reputation. In the end, it was the old lions of Washington instead of the new Young Turks who made the most memorable impression. And it was the old liberal war horses of Congress, erstwhile allies in numerous other battles, whose sharply differing views framed the political divisions that remain today -- both between White House and Capitol Hill, and within Congress itself.

The time: yesterday afternoon, in the dying minutes of the winter of '86. The scene: the chamber of the House of Representatives. The occasion: a vote on a proposal by a strong and popular president to send military and humanitarian aid for the stated purpose of combatting communism in Central America, a vote on which the president placed the full authority and prestige of his office.

The key moment arrived shortly after 2 o'clock. Ten hours of public debate in the House and days of frantic around-the-clock lobbying to win wavering politicians were drawing to an end. In the press galleries above the speaker's well, it was standing room only. In the public galleries across the chamber, every seat was taken. The lines awaiting entry extended down the corridors and for two floors below.

To the podium came Claude Pepper of Florida, at 85 the last of the original New Dealers to serve in Congress, whose first Senate seat was won in 1936 and whose service in the House covers every president from John F. Kennedy to Ronald Reagan. In his early days here he earned a reputation as an ardent liberal, the target of conservatives who jeeringly called him "Red Pepper." Yesterday Pepper, his face flushed, his hands trembling as he gestured toward his fellow members of Congress, delivered an old-fashioned, impassioned speech in favor of Reagan's aid proposal.

He evoked the Cuban missile crisis of 1962, when Kennedy was forced to risk nuclear war, warned his colleagues it could happen again, and said in fiery tones: "My dear colleagues, too many times we have been divided. Today this house of the people is speaking for the people. We are speaking for the hemisphere."

He closed by urging them "to join us in throwing these communists out."

Tumultuous, standing applause from the Republican side of the aisle. Mainly silence from the Democrats who watched as Pepper made his way back to his seat among them.

Down that same aisle lumbered the massive figure of the Democratic leader, Speaker Thomas P. (Tip) O'Neill. He, too, gave an old-fashioned speech, but more quietly delivered. The vote they were about to take was not a matter of partisanship, he began. It was a matter of conscience. He recalled the time he came to the House, in 1952, when waves of McCarthy-era fear swept Washington as patriotism was impugned and lists of the supposedly disloyal circulated, and warned that something of that climate had surfaced over this debate. He evoked the specter of Vietnam, expressed fear the president's Nicaragua policy would "bring our boys directly into the fight," and said: "My conscience dictates that I vote no."

Not so long ago, the Congress would have engaged in another staple of the familiar Washington political drama -- the calling of the roll, with the hushed moment of expectation as an uncertain voter registers his judgment. That suspense has been removed, a casualty of the electronic age. Now, the floor more resembles a milling stock market scene as members gaze upward to see their votes recorded electronically beside their names on the wall. The tension comes with the raw accumulating numbers of the tally and the final count -- and that, of course, was present yesterday.

Yesterday it wasn't close. The 222-to-210 Democratic margin underscored a depth of bitterness among lawmakers over White House tactics.

Before voting against the bill, two southern Democrats expressed resentment at those tactics. Butler Derrick of South Carolina said he had been subjected to the heaviest lobbying he had seen, in his district and in Washington, since he came to Congress a decade ago. "The politics of it are very disruptive," he said, "and I think it's going to hurt the president during the rest of his term. Frankly, it makes me head in the opposite direction."

Freshman Democrat Jim Chapman of Texas, a "swing vote" lobbied by the president and subjected to a TV call-in campaign in his district, said, "You've got to be pretty resilient to get to this place and we're not just offended when our patriotism is questioned. We're incensed by it."