The influence of corporate cash in the democratic process can be seen by the extraordinary length that politicians and lobbyists go to seek campaign donations. Both state and federal investigations have unearthed criminal campaign finance violations by the campaign committees of both political parties at all levels of the election process.
Corporate cash has a big influence in modern politics. Despite efforts at campaign finance reform, this was undone by the United States Supreme Court decision in the Citizens United case. This allowed corporations to give an unlimited amount of money to candidates. Corporations have effective lobbying organizations that are adept at spreading the word.
Even Hillary Clinton, who claims that she doesn't believe in crony capitalism, has taken millions of dollars from corporations for public speaking. It's also widely known that the had pay-to-play access as Secretary of State. We don't have true capitalism in the United States. Rather the corporations buy access which allows them to control the regulations.
I do not think that it could be denied that corporate cash has a major influence on modern politics. As well as helping to fund the campaign of particular delegates it is also apparent that certain interest groups can wield an appreciable amount of power based on their financial contributions.