Campaign contributions have become staggeringly high. In the election of 2008, President Obama received approximately 750 million in contributions. There appears to be a strong correlation between campaign contributions and one's likelihood becoming president. Compared to President Obama, Senator McCain had roughly 350 million in contributions.
The problem with contributions from high interest groups and big corporations is that the money given to a candidate can lead to favors and decisions that can dramatically effect the American people. These favors that are later filled would sway the agenda away from the American people and towards the original contributors.
I suggest a limit of no more than 25 million in contributions per presidential candidate during presidential elections.