Presidential candidate Sen. John Glenn (D-Ohio) appeared to narrow his foreign policy disagreements with President Reagan today, echoing Reagan's alarm over communist subversion in Central America and the need for U.S. military strength to keep the peace as the two vied for political support from the Veterans of Foreign Wars.

Glenn, who is considered by White House political strategists to be potentially the strongest Democratic presidential contender, borrowed a couple of Reagan's 1980 campaign slogans and omitted his customary references to human rights violations and "right-wing death squads" in Central America.

Following Reagan today in speaking before the 84th annual convention of the nation's second largest veterans' organization, which has strongly backed the administration's hard-line approach to Soviet and Cuban intervention in Central America, Glenn said:

"Although we must recognize that most revolutions have their roots in poverty and injustice, the threat of communist subversion that always plays on human misery cannot be denied. Failing to address either of these realities would be a serious mistake."

Glenn said military force should "only be used as a last resort," and he stressed, as has Reagan, the importance of economic aid in encouraging "the forces of justice and the forces of reform" in Central America.

In listing his "principles" for U.S. involvement in developing nations, Glenn sounded Reagan campaign slogans from 1980.

"Never again should we send American troops to fight wars that we do not intend to win," he said, repeating almost verbatim a favorite Reagan line. He picked up another Reagan slogan of "peace through strength," saying that "our military might is for maintaining the peace."

Glenn focused on defense and foreign policy today. His speech included none of the frequent Democratic criticisms about the inequities of administration economic policy.

Glenn has spoken out previously against human rights abuses in El Salvador, and did so only last weekend at a Democratic peace forum in Des Moines. A Glenn spokesman, however, said his speech today "is essentially what he's been saying all along."

The president offered a broad defense of his economic program and also contended that he has brought progress on Mideast peace, in slowing the nuclear arms race, in rooting out Pentagon waste and in rebuilding American defenses.

On Central America, Reagan accused the news media of presenting a "distorted view" of administration efforts to nurture democracy there.

"You wouldn't know from some of the coverage that the greatest portion of our aid to Central America is humanitarian and economic. You wouldn't know that democracy is taking root there," Reagan said. "And I don't blame the media alone, because in many cases they are just reporting the disinformation and demagoguery they hear coming from people who put politics ahead of national interests."

The White House also responded sharply today to news accounts of Reagan's meeting Sunday with Mexican President Miguel de la Madrid. The accounts reported that Reagan had not made progress in advancing his Central American initiatives and that de la Madrid had been critical of the administration's show of force in the region.

"The stories we've seen that indicate the meeting was anything less than a success are way off base," said presidential spokesman Larry Speakes. "It was not the type of meeting designed to change anybody's mind."

Speakes said U.S. differences with Mexico were "minor," and he reiterated the administration's support for the regional solution being pursued by the Contadora group that includes the presidents of Mexico, Venezuela, Colombia and Panama.

Reagan, however, did not mention the Contadora group in his remarks after meeting privately with de la Madrid in La Paz, Mexico, and the two presidents did not close the meeting with the traditional symbolic embrace. The Mexican president had said on Reagan's arrival that the U.S. show of force threatened to touch off a regional "conflagration."

Referring in his speech today to the military "security shield" the administration is attempting to throw up around Central American democracies, Reagan said it was "very much like" the neighborhood watch program in many American communities. The neighborhood watch is where neighbors keep an eye on each others' homes so outside troublemakers and bullies will think twice," he said. The Central America effort "is like a neighborhood watch. But this watch doesn't protect someone's silverware. It protects something much more valuable--freedom."

Today's appearances marked the first head-to-head competition between Reagan and Glenn.

Reagan, who won the VFW's first presidential endorsement in 1980, was received warmly by the audience of 2,000 veterans and their wives at the Rivergate convention center here. When Glenn followed a half-hour later, about half the audience had left the hall and the response was noticeably less effusive.

Reagan faulted the Democrats for "special interest politics" in a speech last Saturday to a Hispanic group, but today he practiced, as he has before, what he warned them against. After his speech, the president moved to a table on the stage where the conventioneers watched him sign an emergency veterans job training bill.

Although Glenn allied himself with some of Reagan's foreign policy themes, he and the president sought to draw distinctions between each other. Reagan made pointed reference to the need for the MX missile, which Glenn has opposed, saying it would give the Soviets "incentives to negotiate reductions in nuclear arms today."

Glenn repeated his frequent criticism of the Reagan defense buildup as "putting the military cart before the foreign policy horse."

"What some people still don't seem to understand is that in a world of infinite demands and finite resources, we simply cannot do everything," he said.

Copies of Glenn's speech had been distributed here a few hours before the presentation, and Reagan, who spoke first, tried to preempt the Glenn complaint about the defense buildup. Reagan insisted that the administration's military objectives are "based on what we think are all the possible contingencies." The speeches included some political jabs at each other.

Glenn, a former Marine colonel who flew 149 combat missions in World War II and the Korean War, indirectly reminded the veterans that Reagan did not serve in combat.

"We've seen the horrors of war," he said, "and we didn't need to watch late-night television to find out what it's like."

Reagan did not run from his Hollywood combat days. As he took the podium, he said, "Since that applause is coming from veterans, I have to ask, is it for how I'm doing my job, or how I'm doing in the late-late show in 'Hellcats of the Navy'?"

The White House originally had turned down the VFW invitation, but after heated complaints, Reagan ordered the trip scheduled after his meeting with de la Madrid. Reagan did not remain in the convention hall long enough to hear Glenn's speech. He flew on to his Santa Barbara ranch before campaigning again next week.