You can be influenced in a caucus or primary.
In the former, debate takes place among your fellow citizens, this does require reasoned argument, perseverance and sometimes cajoling. I have heard corporate media conglomerate pundits cite caucuses as being "undemocratic" which is kind of ridiculous since the caucus process gets to the heart of what the First Amendment is all about, freedom of speech and its potential impact on political deliberations, along with community participation.
In the latter, people are influenced in primaries as well but in this case by the the six corporate media conglomerates (which control 90+% of everything the American People see on television, hear on the radio or read in printed publications) after months if not years of their narrow minded, propaganda based on their corporate self-interest which in many cases is far removed from the most critical issues that affect the average American. The primary votes are done in private as "individuals" and the corporate media conglomerates would much prefer we keep that mentality as it makes dividing and conquering all the easier.
I've noticed the corporate media conglomerates to be quick in criticizing the caucus process because of the "influence" or "persuasion" put on the voters as opposed to a primary; in which case someone can just go and vote in private. What the corporate media conglomerates really hate or fear is that caucuses allow an end run of sorts around or through their long entrenched corporate media propaganda and conditioning of the people.