Lyndon B. Johnson left behind no foreign policy doctrine. But he had deeply held convictions about the perishability of the powers of the president that might have been raised to the level of a doctrine if he had stated them publicly. They bear directly on the current condition of Ronald Reagan in the wake of a sound defeat at the hands of Congress on the issue of "covert" military support for the Nicaraguan contras and the subsequent battering of his budget by the Senate.

The Johnson doctrine begins with the belief that a president cannot cut a commanding figure on the world stage if he is not perceived to be in command of his own political processes. Johnson even carried the argument to the conclusion that just one defeat in Congress on an issue deemed vital to a president's interests could be crippling beyond repair.

It's true that, in the instant case, President Reagan took the initiative to abandon his insistence on military aid and slipped from sight when it became obvious he could not win. But that cannot alter the perception that he spent heavily from political capital -- and lost.

That's something under the Johnson doctrine that a president, even with a landslide election victory, cannot afford to do. Regularly, Johnson warned his advisers that he had only at best a limited supply of political capital. It was to be husbanded for propositions with a reasonable prospect of acceptance, or for emergencies.

Political savants by and large accept the Johnson doctrine, in theory. The question is whether it applies in practice to Ronald Reagan. Does his particular political magic render him immune? Or is his fabled Teflon presidency already damaged goods? Veteran Reagan-watchers, harking back to his days as California's governor, advise caution: He has been down before and bounced back.

But he is plainly not bouncing back in the battle over his budget in the Senate, having lost not only on his cherished defense budget but on Social Security spending cuts as well. There is then more than enough recent evidence of unfamiliar fallibility in the performance of the second Reagan administration to suggest a certain relevance of the Johnson Doctrine to Ronald Reagan's case. Even before the mindless bungling of the preparations for his European trip, the president had dipped deeply into his political bank account to win a narrow and perhaps hollow victory on the MX missile. By his inability to dig himself quickly out of the disaster he had dug himself into with his European itinerary, the president squandered further political capital.

So the loss on the key issue of military aid to the contras came at a time when a lot of people were already beginning to wonder whether the second Reagan administration had somehow lost the first Reagan administration's fine touch for those tricks of the trade that serve the Reagan presidency best: imagery, symbolism, communication, the projection of "leadership."

Johnson finally lost command by losing control of events, and appearances, in about February 1968 with the Tet offensive in Vietnam. But generally he did not risk his prestige on behalf of controversial propositions unrelated to his larger Great Society designs. Witness the way he overruled some of his most trusted foreign advisers on an issue that confronted him after his election in 1964.

It was more earth-shaking a deal than the relatively piddling $14 million funding for the CIA guerrillas in Nicaragua. The question was whether the United States would participate in a multilateral nuclear force (MLF). It was to be an experimental mini-armada of surface ships, mix- manned by NATO crews and armed with Polaris missiles whose nuclear warheads would be under American control. But Johnson was unpersuaded that the Europeans wanted it. More to the point, he didn't think Congress wanted it.

In a decisive meeting in December 1964, he killed the idea after giving his assembled advisers a lecture on presidential and congressional politics. He was not carried away by any election "mandate." He doubted Congress was impressed; he knew how fickle public opinion can be. He was not going to do "another 1919" (a reference to Woodrow Wilson's control over Congress). Neither did he intend to do another "1937" (a reference to Franklin Roosevelt's "court packing" scheme whose rejection he believed did Roosevelt permanent damage on Capitol Hill).

As usual, he had a story from Texas to embellish his argument. It was of a cowboy who saved up all year to buy a bottle of whiskey and a string of firecrackers and consumed both on New Year's Eve. "I worked like hell to get to be president," Johnson said, "and I don't want to set it all off at once."

Now it is true that LBJ never laid claim to charisma -- certainly of the kind that Ronald Reagan can rightly lay claim to. So we will have to wait and see whether Reagan is the exception to a well-recognized rule.

What can be said with certainty is that Reagan's recent handling of the money for the contras was in clear violation of the Johnson Doctrine: Wise presidents do not invite senseless showdowns with Congress in a way that puts the power of their presidency at risk.