Chester A. Arthur
Abraham Lincoln was the first President to rock the beard... with no moustache! But he openned the facial hair door to men like Ulysseus S. Grant. But it was Chestur A. Arthur who pioneered the beardless Presidential Moustache-- and he did it with style!
He kept light mutton chops, probably at the request of his wife. Because what wife wouldn't want to not only be married to the President, but have a husband with mutton chops?
We may never know why he kept them; he was famous for saying "I may be President of the United States, but my private life is nobody's damned business."
...Bill Clinton should have remembered that precedent. And grown mutton chops too.
Additional Note: Chester A. Arthur was accused of being born in both Ireland and Canada during his electioral seasons. Ironically, he was in fact a Kenyan Muslim who conspired with newspapers to alledge a Hawaiian birth!