With his own post-debate polls confirming a widening gap in his effort to catch President Reagan, a game and emotional Walter F. Mondale vowed today to give the campaign "everything I've got" in its 11 remaining days.

Campaign chairman James A. Johnson said today he told Mondale at a Wednesday night strategy session in Milwaukee that public and private polls taken after last Sunday's foreign policy debate indicated that "there appeared to be some drift to Reagan."

The Boston Globe reported today that Johnson had told Mondale that Reagan has what appears to be an insurmountable lead.

Johnson said he also told the Democratic nominee that release of the poll data could create further political problems for the Mondale campaign. He declined to disclose specific findings of the Mondale surveys.

The latest Washington Post-ABC News poll, taken after Sunday's debate, showed Mondale trailing Reagan by 12 points, the same margin as before the face-off. A Harris Survey released Thursday showed Reagan with a 14-point lead -- 5 points wider than the week before.

According to those who attended the Wednesday night meeting, Mondale cut off the conversation about polls and instructed others in the hotel suite not to dwell on them. He also said the numbers did not jibe with his own sense that crowd reaction has been increasingly positive.

"Jim pointed out it's tough and we all know that," Mondale told reporters this morning in Flint, Mich., "but . . . I think these polls are dead wrong. I think we've got an excellent chance of winning. The crowds are enormous . . . .

"And I'm giving this campaign everything I've got," he added, eyes moist with passion, "because this is America's future that's at stake. And I don't care what the polls say. I know that the American people are going to make up their minds based on what's best for the country. Americans don't trifle with the future."

Mondale said he did not believe that the Reagan lead was insurmountable, and aides in Washington echoed that view.

"I think it's a temporary move and we have no basis for believing there's any substantial momentum to it," Johnson said of Reagan's widening lead. "We think that the response Mondale is getting now from his campaign is so strong that we believe there is a better and better chance every day of him winning this race."

"We're premising our behavior in the next 11 days on not paying much attention to the polls," senior campaign adviser Richard C. Leone said. "The key to our victory is a lot of volatility in the last five or six days. From now on, we think the race is just a flat out sprint."

So began for Mondale one of the most difficult chores for any longshot campaign in its closing days -- momentum control. His strategists have always said they can win only with with a massive turnout, and nothing dampens voter enthusiasm more than the scent of certain defeat.

That appeared to be some of the thinking at the Wednesday evening strategy session, which took place at the Marc Plaza Hotel in Milwaukee. Afterward, en route to a political rally in Cudahy, Wis., Mondale told reporters he would discuss no more polls until after the Nov. 6 election.

Today, he campaigned as anything but a loser, unloading on Reagan for commemrating the first anniversary of the Grenada invasion but not marking the anniversary of the bombing in Beirut that killed 241 U.S. servicemen two days before the Grenada strike.

"On the anniversary of the Lebanon bombing, the president spent the whole day campaigning against me and not one minute remembering them," Mondale told a downtown rally. "No speech. No ceremony. No president . . . . Doesn't plain deceny, beyond politics, dictate some recognition of those that lost their lives . . . .?

"Today, we have a happy talk president who's only around for the good news. It's all celluloid. All media managers. Today we have a sunshine president and what we need is a president for all seasons.

"To them, if you're unemployed, you're on your own. If you lost your farm, it's too bad. If you're too old, tough luck. If you're sick, good luck. If you can't afford college, so what? If you're handicapped, you shouldn't be.

"That's not what a president should be . . . . As president, I'll be with you in victory and setback; in joy and in mourning; in hope and in need."

Reagan, he concluded, sees Uncle Sam "as a kindly old man with a spine of steel . . . . I want to see an Uncle Sam with a mind and a heart and a soul and a conscience."

Earlier in the week, Mondale had been hammering Reagan for "not knowing what he must" about arms control and nuclear weaponry. Now the competence argument has been supplanted by talk of values and vision and fairness and compassion.

"It was a call Fritz made from his gut," senior adviser John Reilly said today. "He felt as though he'd reached a plateau where people were listening, and he wanted to get down to basics."

Other aides privately acknowledged that the case they wanted to make out of the second debate, that Reagan is not up to the job, simply never took hold as they had expected.

Mondale's current campaign swing, through the Midwest and the Northeast, into Texas today and eventually to the Pacific Coast for three days of weekend stumping, underscored his desperate scramble for an Electoral College majority.

In nearly every state poll taken since Labor Day, Mondale has run so far behind Reagan in so many states that an Electoral College victory seems all but impossible, and Reagan's chances for an electoral rout appear possible.

The Mondale victory plan is based on winning nearly half the necessary votes from about a dozen scattered states where the Carter-Mondale ticket did best in 1976 and 1980, including Massachusetts, Pennsylvania, New York, Wisconsin and Minnesota.

A hefty chunk of the remaining 140-odd electoral votes would have to come from six of the most populous states -- Illinois, Michigan, Ohio, New Jersey, California and Texas. Carter did not win all those states, and more than likely, neither will Mondale.

Carter, a Georgian, was boosted to victory by solid southern support. Mondale is trailing Reagan in the Deep South by a margin of nearly 2 to 1, though aides entertain some hope in Georgia and Arkansas.

Thus, Mondale's victory margin would have to come from places like Washington and Oregon, where the Democratic nominee has been running relatively well in recent polls.

The rest of the difference will have to be made up by a near sweep of the Midwest and Northeast, scattered victories in border states, including Tennessee, Missouri and Kentucky, and maybe even a slight lift from tiny Vermont, Maine or Delaware.