Words that define a presidency

Mostly Cajun writes that on this day in history

1987 – Cold War: U.S. President Ronald Reagan publicly challenges Mikhail Gorbachev to tear down the Berlin Wall at the Brandenburg Gate. It becomes a defining moment of the Reagan presidency: “Mr. Gorbachev, tear down this wall!”. For Bill Clinton, it’s “I did not have sex with that woman, Monica Lewinsky!” One can only speculate what the defining words of the Obama presidency might be.

Any ideas on that subject?