The health of Philippine President Ferdinand Marcos has taken a turn for the worse, and he is so weakened that he has had to be propped up by bodyguards during recent campaign rallies and has cut back road appearances for next month's presidential elections, well-informed sources in Washington said yesterday.

Marcos, 68, suffers from an often incurable, recurring illness known as systemic lupus erythematosus, according to intelligence and congressional sources. The disease causes inflammation of many body systems and can have serious impact on the kidneys.

Marcos has survived three debilitating bouts, recovering each time to resume his activities. According to sources, he may be suffering another bout that began shortly after the new year. His poor health has raised particular concern among Marcos' senior aides as the presidential campaign enters the critical last three weeks before the Feb. 7 election, the sources said.

Marcos, who has been in power for 20 years, is being challenged by opposition leader Corazon Aquino in the toughest political race of his life. Some U.S. officials say that the race appears to be narrowing, and Aquino could win at the polls, or come close, but that Marcos is likely to emerge the winner after the votes are tabulated. Marcos' health is one of the critical wild cards in the election.

Observers say recent reports from Manila describe Marcos as looking "terribly fatigued and exhausted." They say this downturn is likely to result in Marcos staying at Malacanang Palace, limiting his appearances to television broadcasts or press conferences and leaving out-of-town appearances to his running mate, Arturo Tolentino, 75, and to Marcos' wife Imelda.

In an appearance yesterday in Pangasinan Province north of Manila, security agents had to carry Marcos, visibly tired, to the stage during a campaign rally in Dagupan, a stronghold of Marcos' ruling party, according to a report from the French news service Agence France-Presse. Marcos had difficulty raising his hands to flash a victory sign to approximately 10,000 supporters and appeared to be in pain and breathing heavily. Moments later, he was encircled by security men and local political leaders on the stage and could not be seen for about 30 seconds.

After chanting from his supporters died down, two men in white went to the president's seat and affixed something on the back of his hand, which had a small bandage. Later he was escorted to a curtained room at the back of the stage and stayed inside for about two minutes. When he came out he seemed to have recovered.

During a speech earlier in the day at the nearby town of Urdaneta, Marcos apologized for having a cold, the French news agency reported.

In the past, Marcos has said problems with his health are related to shrapnel wounds that he suffered during World War II. He has vehemently denied reports that he has had a kidney transplant. In his previous bouts of the recurring disease, Marcos has recovered, but each time to a "lower plateau," U.S. officials have said.

A boat trip that was scheduled last week for a campaign stop in the Visayan region, in the central Philippines, was canceled, sources said, and there had been reports in Manila that previous campaign appearances had been canceled. Since the campaign began a month ago, Marcos has visited at least six of the country's 73 provinces, while Aquino and and her running mate, former senator Salvador Laurel, have traveled to more than half of the provinces.

At a press conference in Manila last week, Marcos denied that he had canceled campaign stops for reasons of poor health. A spokesman at the Philippine Embassy in Washington yesterday described him as being "at the peak of health." The spokesman said the president had canceled some of his campaign appearances last week because he needed to stay at the presidential mansion to oversee other pressing matters, such as the reorganization of the military.

Asked about the incident in Dagupan, spokesman Rey Naval said security guards at the rally carried the president because "there were so many people in the crowd who wanted to shake his hand, they had to carry the president to allow him to go to the stage and start the festivities."

Naval dismissed speculation that Marcos could have been receiving medication while off the stage, saying, "He could have just been having an orange drink."

If Marcos' health should deteriorate to the extent that he is no longer able to function, or if he dies before the election, under the Philippine constitution, succession would pass to the speaker of the National Assembly, Nicanor Yniguez. Yniguez is believed by some analysts to be loyal to Imelda Marcos, who acts as roving ambassador for her husband and who has been seen for years as his possible successor.

It would then be up to Yniguez to decide whether to proceed with the election or to put it off to allow the ruling party to nominate another candidate. One candidate who has been mentioned by senior Marcos aides is Defense Minister Juan Ponce Enrile, according to sources in Washington.

Should Marcos win the election and then die, the succession would pass to the vice president, who would serve out the six-year term.