Sen. John Glenn (D-Ohio), who hopes to become the next president, suggested yesterday that Social Security perhaps could be made more solvent by creating a voluntary, partly private alternative program "for people in their younger years."

Glenn voluntarily indulged in the politically incendiary issue during a breakfast meeting with reporters.

"I'm not making a proposal," he said. "I'm saying that it is a possibility."

Other possibilities, Glenn said, would be to push back the eligibility age for benefit payments from 65 to 68 for persons not yet receiving benefits. And he said the cost-of-living increases for Social Security benefits could be reduced, or even eliminated.

He also conceded, at the end, that he might have created political problems by venturing into this political brier patch, which his fellow politicians have avoided in the name of survival.

"Maybe I did get into political hot water," he said later. He said he meant to make clear at the breakfast that he was talking only about ideas that he heard were being discussed by the presidential commission on Social Security headed by economist Alan Greenspan.

"I've not proposed any ideas on how we should fund Social Security," he explained. "I've stayed away from that like the plague."

Glenn opened up the subject after saying the current huge budget deficit was caused in part because "we were laggard" in not modifying a number of programs. When a reporter asked him what programs he had in mind, the senator listed food stamps, which he said "no one envisioned" that 21 million people would eventually be receiving, entitlements programs in general and Social Security in particular.

There should be no changes that would affect persons already receiving Social Security benefits, Glenn said.

"Those persons . . . have a contract and a sacred trust" with the government, he said. "They can't adapt like others can."

But he went on to say that perhaps the eligibility age should be pushed back to 68 "and maybe we should go back to less COLAs cost-of-living adjustments or no COLAs."

Later in the breakfast, Glenn talked about the possibility of a "quasi-governmental private investment program . . . for people in their younger years."

"People in their younger years could volunteer to go on a program that would be part in the private sector and part in government" but with the government guaranteeing a lesser portion of the program, he said.

In response to another question, Glenn said he did not think it would undermine the Social Security System if people had the option of choosing another program. "If it's done over a long period of time . . . you could phase it in over 25 to 30 years."

Later Glenn said he did not mean that people should be able voluntarily to exclude themselves entirely from the Social Security program, just from a portion of it.

"Everybody should be within the Social Security System in some way," he said.

Suggestions for reforming the Social Security System often are quickly followed by political discomfort and, occasionally, disaster. It happened to Barry Goldwater in 1964.

Most recently, in California, the Republican candidate for senator, Pete Wilson, suggested a voluntary, partly private alternative Social Security program, and promptly revitalized the troubled campaign of his Democratic opponent, Gov. Edmund G. (Jerry) Brown Jr.

"When I talk about a voluntary Social Security program, I'm not talking about the same thing Wilson is in California," Glenn said.