In last 100 years, only 1 Republican defeated incumbent Democrat president

I heard this quote from Republican Presidential candidate Rick Santorum on the radio this morning and I found it in a Newsmax article on Santorum's discussion with CNN’s John King (emphasis is mine):

Santorum noted that the Republican establishment in Washington and New York typically pushes for a moderate like Romney to lead the party, and they typically lose.

“ … if we don’t have a conservative, we will end up with the same situation we have had over the past 100 years. There’s been over 100 years now. There’s only one Republican that’s ever defeated a sitting Democratic incumbent president, one.

“And it’s the one time we ran a strong conviction conservative, in the face of the party saying no, no, no, we need a moderate. We need to win. We need to win. They always say that. And we always lose. And the one time we didn’t listen to the establishment, the Washington insiders, we had Ronald Reagan. And not only did we win. We changed the country.”

Before Reagan defeated Jimmy Carter in 1980, it was 1888 when such an upset occured.  Grover Cleveland was defeated by Benjamin Harrison.

There's a very powerful lesson to be learned here - but I don't know if anyone is paying attention.