All eyes are on Denver, Colorado where Republican Mitt Romney hopes to regain ground lost in recent days to Democrat Barack Obama at the first presidential debate.

History has proven that presidential debates can be game-changers. Richard Nixon was challenged by his opponent John F. Kennedy to a series of televised debates, the first in American history.

The Nixon Kennedy debates would forever change the way Americans chose their presidents as political rallies became much less important than the image on the television screen.

The first debate was costly to Nixon as the radio audience thought he had won, but the largest television audience in history instead said Kennedy won.

They went into the night tied, but Kennedy promptly surged into the lead.

The 90-minute showdown will be the first of three televised Obama vs Romney encounters in October that will set the tone for the final month of the presidential campaign.

The debate will be held Wednesday at 9 p.m EDT at the University of Denver.