<P> The Republican Party's current ideology is American conservatism, which contrasts with the Democrats' more progressive platform (also called modern liberalism). Its platform involves support for free market capitalism, free enterprise, a strong national defense, deregulation and restrictions on labor unions . In addition to advocating for conservative economic policies, the Republican Party is socially conservative and seeks to uphold traditional values based largely on Judeo - Christian ethics . The GOP was strongly committed to protectionism and tariffs from its founding until the 1930s, when it was based in the industrial Northeast and Midwest . Since 1952, there has been a reversal against protectionism and the party's core support since the 1990s comes chiefly from the South, the Great Plains, the Mountain States and rural areas in the North, as well as from conservative Catholics, Mormons and Evangelicals nationwide . </P> <P> As of the 2017 elections, the Republicans are the primary party in power in the U.S., holding the Presidency (Donald Trump), majorities in both the House of Representatives and the Senate, a majority of governorships (34 / 50) and state legislatures (full control of 32 / 50, split control of six others). </P> <P> Founded in the Northern states in 1854 by anti-slavery activists, modernizers, ex Whigs and ex Free Soilers, the Republican Party quickly became the principal opposition to the dominant Democratic Party and the briefly popular Know Nothing Party . The main cause was opposition to the Kansas--Nebraska Act, which repealed the Missouri Compromise by which slavery was kept out of Kansas . The Northern Republicans saw the expansion of slavery as a great evil . The first public meeting of the general "anti-Nebraska" movement where the name "Republican" was suggested for a new anti-slavery party was held on March 20, 1854, in a schoolhouse in Ripon, Wisconsin . The name was partly chosen to pay homage to Thomas Jefferson's Republican Party . </P> <P> The first official party convention was held on July 6, 1854, in Jackson, Michigan . By 1858, the Republicans dominated nearly all Northern states . The Republican Party first came to power in the elections of 1860 when it won control of both houses of Congress and its candidate, Abraham Lincoln, was elected President . It oversaw the preserving of the Union, the end of slavery, and the provision of equal rights to all men in the American Civil War and Reconstruction, 1861--1877 . </P>

Who were the leaders of the opposition republican party