Viktor Yushchenko was a political heartthrob, fueling his meteoric rise in the Ukraine with his movie-star good looks and telegenic public presence, ABC reported.

Together with his striking American-born wife, the two made an appealing, energizing power couple.

But there has been an astonishing transformation. Over four trying days in September in the middle of his David vs. Goliath run against the Moscow-backed political establishment, the once-robust 50-year-old Yuschenko fell mysteriously ill.

SLIDESHOW: Ukraine Presidential Candidate

"The dramatic changes that you see in Yushchenko are extreme," said Dr. Barney Kenet, a dermatologist at New York Presbyterian Hospital. "There is swelling of his eyelids, his nose, and an overall enlargement of his face with pebbly skin."

What caused his sudden transformation has baffled some of the best European doctors, ABC reported. And his story has quickly taken on all the qualities of a spy novel.

He accuses his political opponents of poisoning him. His doctors are investigating whether his symptoms were the result of biological weapons.

One specialist received death threats while treating him, and asked for police protection, ABC reported.

Through it all, the indefatigable politician is leading a widening and exhausting popular rally against the election last weekend that, he says, unfairly denied him his country's presidency.

ABC reported he vows to keep fighting and says that nothing can make him give up.