A primary election is an election that narrows the field of candidates before the general election. Primary elections are one means by which a political party nominates candidates for the next general election. Primaries are common in the United States, where their origins are traced to the progressive movement to take the power of candidate nomination away from party leaders and give it to the people. In the case of closed primaries, only party members can vote. By contrast, in an open primary all voters may cast votes on a ballot of any party.