Less than three weeks ago, Peter A. McKernan stood strong and tall at his father's side, beaming with pride as John R. McKernan was sworn in for his second term as Maine's governor.

That moment of triumph has given way to tragedy. Now the governor maintains a vigil at the bedside of his only child, who is clinging to life after suffering heart failure.A bright, athletic, easygoing reflection of his father, 20-year-old Peter had just finished a two-mile jog with other students hoping to make the baseball team at Dartmouth College in Hanover, N.H., when he collapsed Jan. 14.

Since then, the blond sophomore has been hospitalized in Hanover in extremely critical condition, in a coma, breathing with help from a ventilator. Doctors say his chances of recovery are remote.

The governor, spending virtually every waking moment by his son's side, "is in a lot of pain," said Sharon Miller, McKernan's chief of staff and friend. "Peter's the most important thing in his life."

Miller said the elder McKernan, 42, has remained strong throughout the ordeal, though "this is truly the most devastating thing that can happen to a human being."

"He's just remarkable, comforting others while grieving himself," Miller said.

McKernan's wife, U.S. Rep. Olympia Snowe, R-Maine, and Peter's mother, Judith Vigue, also have remained at the hospital.

Peter's attending neurologist, Dr. Richard Nordgren, says brain swelling makes the likelihood of recovery remote. He says the cardiac arrest probably was caused by an electrical disturbance that would not necessarily be detected in routine medical screening and could be hereditary or caused by a viral infection, cardiologist Dr. Bruce Friedman said.

Tests indicate drugs are not involved.