That was the first thing that popped into my mind, too. Something along the lines of Obama, Mao, Lenin, Stalin being con substantial fellow travelers.
“Consubstantial” — some English words just don’t roll mellifluously off the tongue, do they? I think the popularity of words depends somewhat on their musicality to the ear and “Consubstantial” gets an F in that department.
See #7. The Catholic church pulled this one out of the hat a couple of years ago. We say it at every Mass, but it doesn’t come easy.