President Reagan looked wonderful the morning after the MX vote in the House, as well he might.

He called a little press conference to hail an important victory for arms control. His eyes were bright, his cheeks rosy. He had been assured once again that fear of him remains the prevailing political fact in Washington. He got 40 votes fewer than he had in May, but to have won at all, in consideration of what is not happening in Geneva, was, he must have known, more than he deserved.

As before, the Democrats did his heavy lifting for him.

Reagan's successes with Congress make manipulator Lyndon Johnson look like an amateur. LBJ used dams and dinners. Reagan has elevated the "national bipartisan commission" to an art form. He stacks these assemblages with people who agree with him, ropes in a few conspicuous Democrats to serve as Judas-goats, gives them a peek at the cable traffic and sends them off to lead the charge for him on the floor.

The Scowcroft Commission, a collection

of hawks, all

pro-MX, was

supposed to

make a study

of a new bas ing mode for

the monster.

Actually, they

made a shrewd study of Democratic needs and obsessions in the nuclear field.

The basing mode they chose was a joke, but it didn't matter. They offered Rep. Les Aspin (D-Wis.) and Rep. Albert Gore (D-Tenn.) the feeling that they were at last sitting at the grown-ups' table and making arms control policy.

Aspin became an apostle of the politics of fear. He told his fellow Democrats they should consult their fears rather than their convictions in voting for the MX.

Said he to Elizabeth Drew, author of a masterly account of the controversy in The New Yorker: "Sure, I think the Democrats could make the case that it's a silly weapon. But the issue is arms control, and if we gave him the argument that he had appointed a bipartisan commission and was willing to go in a new direction but the Democrats wouldn't let it happen."

In other words, be a coward, it's safer.

Aspin subsequently went further during the recess. He spared the president the need to inform pro-nuclear-freeze Democrats, who include their leading presidential candidates, that they look soft on defense.

What Aspin was doing was no different from what other Democrats do for the president.

For instance, Speaker O'Neill never passes up an opportunity to speak harshly about the Albosta Committee, which is looking into the potentially embarrassing matter of the pilfered Carter papers. And Rep. Dante Fascell of Florida, a senior Democrat on the House Foreign Affairs Committee, is a vocal defender of the president's secret war in Nicaragua.

The power of the MX commission, its value as a privileged sanctuary for timid Democrats, was attested to during Thursday night's debate on MX revisited. Rep. Joseph Addabo (D-N.J.), who in May had told his colleagues that the vote (on testing the MX) was not a vote for the Scowcroft Commission, not a vote for the single-warhead missile, not a vote for arms control, but a vote for MX, had changed his tune on Thursday night.

A vote to stop deployment, he said rather desperately late at night, was really "a vote for the Scowcroft Commission."

Now the Democrats are about to troop down the garden path once more. Reagan has formed a "national bipartisan commission" on Central America. Its sponsor -- Sen. Henry Jackson (D.-Wash.) -- and its designated chairman -- Henry Kissinger -- should be warning enough about what is coming down.

The former secretary of state and destabilizer of Chile never made any secret of his indifference to Central America, which is so remote from Big Powerdom. According to Seymour Hersh's unauthorized biography, "The Price of Power," Kissinger told Gabriel Valdes, Chile's Foreign Minister in Christian-Democrat days, "The axis of history starts in Moscow, goes to Bonn, crosses over to Washington and then goes to Tokyo. What happens in the South is of no importance."

But the Democrats are not reading the Hersh biography. They are reading their fear that Reagan will accuse them of "losing El Salvador" if they don't give him what he wants.

Rep. Michael Barnes (D. Md.), who has opposed Reagan's policy in the past, has signed on as "congressional counselor" to the body. Sen. Paul Tsongas (D.-Mass.), who knows better, says the commission is a good idea.

Reagan may be in trouble with various voting blocs around the country, with blacks and women, but in Washington he is sitting in the catbird seat. That is because he has discovered that what congressmen want more than anything in the world is to be let off the hook when it comes to difficult choices.