I'm sure most people if not all people know politics is corrupt. As we've seen in the past politicians will commit acts that will move their agenda(s) forward which includes financial contributions. In order to deal with this and minimize the amount of shadiness that could go on this practice should be banned. Unfortunately, we cannot trust that sending money to people with/in (potential) political power to be fueled by good intentions.
Elected officials in the United States are supposed to represent the people, not lobbyists and corporations. When elected officials receives a lot of money from certain groups, even if they don't want to let that influence their decisions, it probably does, even on a subconscious level. It's unfair if lobbyists and corporations have a greater ability to influence elected officials than the average person. Political campaign contributions need to be limited more and restricted.
Financial contributions from political action committees and lobbyists representing major corporate interests should be banned in the United States because candidates running for political office should only be accountable to the citizens of America and not its corporations. The interests of American citizens are often not the same as the interests of corporations. The government's propose is to protect and advocate for citizens, not corporations.
PAC's and lobbyists should be banned from directly contributing to political campaigns and candidates. Especially with campaign finance laws weakened due to Citizens United v. FEC, the amount of money used to gain influence in politics is obscene, and candidates who limit themselves to donations from private citizens have almost no chance of keeping up. Political figures who accept large donations from lobbyists and corporations are also more likely to vote in favor of the interests that continue to fund their career.