Ballot access is permission by the government for a candidate for public office to appear on the electoral ballots. In some jurisdictions, major party candidates are automatically placed on the ballot, while minor party candidates have to circulate petitions and gather a certain number of voters' signatures in order to be placed on the ballot. Ballot access laws are often used to require minor parties to devote their resources to having volunteer or paid petitioners attempt to cajole county fairgoers, passers-by outside grocery stores, and so on, into signing their petitions; this is often difficult, as such people are typically more concerned with other priorities than with politics. Then again, that could be said of almost any interaction with voters; it tends to be a struggle to get them to devote much time to listening to a candidate, especially an unfamiliar candidate, and perhaps most especially an unfamiliar candidate who, because of his third-party status, has little chance of winning, probably adheres to a non-mainstream view that few voters will find palatable, and could prove to be a spoiler in the election, for good or bad.
Ironically, the ballot access laws that were intended to prevent Socialists from getting on the ballot in Oklahoma now make it quite difficult for the U.S. Libertarian Party to get its candidates on the ballot there.