Is the donkey a wimp when it votes against the MX missile? Or is the wimp a real donkey when it bows down on the MX because President Reagan is beating it like a peasant heading to market?

Those were the two questions facing the House Democrats on the matter of the $1.5 billion authorization for 21 more of the monster missiles that the president calls "Peacekeepers."

Rep. Patricia Schroeder (D-Colo.) defined the issue in piercing tones early in the day. "We've all become afraid of being called a wimp," she said, to the discomfiture of her Democratic colleagues. "I say we are a wimp if we roll over and go along with this. We are wimps if we don't stand up to the kind of reasoning which says that this is a bargaining chip."

Sixty-one Democrats, reaching a judgment on true wimpiness, defected to the Republicans, in the interests, they said, of advancing Reagan's stated goal of eliminating nukes from the face of the Earth.

Rep. Les AuCoin (D-Ore.) noted sardonically that some people had, like the president, opposed all previous arms accords but suddenly had gotten religion when the MX hit the floor. "Let us not pretend we are doing it for arms control," he said.

But the members were beyond reason. On both sides, they did the ritual moaning and writhing, putting aside their contempt for a flawed and vulnerable MX only in the interest of making progress in Geneva.

Rep. Frank Horton (R-N.Y.) said, "I am not a supporter of the MX" just before he voted aye. In his district, 200 constituents had opposed the weapon and had expressed concern about the unstoppable arms race. But negotiator Max M. Kampelman said he needs the MX at the bargaining table and left Horton defenseless.

The only new rhetoric was provided by the portly, booming Rep. Henry J. Hyde (R-Ill.), who did not call MX a dog but offered a canine analogy. He announced that he didn't want to send our team to Geneva with a "poodle on a leash." He wants to provide them with a Doberman pinscher.

The Republicans gratuitously baited the Democrats about the November returns.

The Republicans did not need to say it. The Democrats were saying it for them. Rep. Charles Wilson (D-Tex.) said the Democrats have become somehow the party of isolation and weakness on defense, at least in the South and the West, and, if the perception persists, "we can forget all about presidential elections."

And Rep. Carroll Hubbard Jr. (D-Ky.) said Reagan had swept his 92 percent Democratic district: "My constituents are saying we trusted him on Nov. 6, and we trust him on March 26."

The "weak on defense" argument had been introduced by the Democrats' leader, House Speaker Thomas P. (Tip) O'Neill Jr.(D-Mass.), when he insisted that the Senate go first on the MX. He turned his troops loose on the issue, thereby inviting them to consult the polls rather than their common sense. He watched glumly while scores of them advanced to the conclusion that it is better to be losers than wimps.

They were awash in chagrin before the afternoon was over. Rep. Charles E. Bennett (D-Fla.) led the fight against the MX. They did not listen too attentively. But when he finished and was making his way laboriously back up the aisle with his canes, they gave him a standing ovation.

It was cheer of conscience. They had rejected Bennett for chairman of the House Armed Services Committee in favor of Rep. Les Aspin (D-Wis.), the glib "defense philosopher" who, in his campaign for the chairmanship, had led several of them believe that he would help kill the MX this time.

Aspin, who provided a convenient hat rack for troubled Democrats, spent much of his time off the floor huddling with the White House congressional liaison, counting votes for the president.

He was the last speaker and gave the ultimate offense to those who regard him as a traitor.

"To remove these missiles by a no vote," he said, "would in effect be giving some help to the Soviet Union."

The hissing began in the middle rows where his former friends were sitting. It turned into a kind of growl.

Aspin got a standing ovation from the Republicans.

Outside, Rep. Howard E. Wolpe (D-Mich.), one of those who believed he had Aspin's anti-MX pledge, ran into Fred Wertheimer of Common Cause, an indefatigable anti-MX lobbyist. Wolpe said, "I feel like an absolute schmuck."

That's the way many Democrats feel, except, of course, those who don't mind losing a vote on the arms race as long as they think they are winning on the "wimp" problem.