The Republican Party (often referred to as the GOP, for "Grand Old Party") is one of the two major political parties in the United States' two-party system, along with the Democratic Party. In the modern political era, the Republican Party has been the more socially conservative and economically libertarian of the two major parties. The Republican symbol is the elephant, and its unofficial color is red.  As with the Democratic Party, the adjective 'Republican' is purely historical, and does not indicate any distinguishing value with regard to other parties.
The Republican Party was established in 1854 by a coalition of former Whigs, Northern Democrats, and Free-Soilers who opposed the expansion of slavery and held a vision for modernizing the United States. The party initially had its base in the Northeast and Midwest, but in recent decades it has increasingly shifted to the inland West and the South.
Since the party fielded its first presidential candidate, John C. Frémont, in 1856, 18 of the 29 United States Presidents have been Republicans, including current President George W. Bush. It holds 28 out of 50 governorships, and controls 20 state legislatures compared to the Democratic Party's 19.
By custom, the sitting president is the leader of his party; President Bush selected Ken Mehlman as the chairman of the Republican National Committee in January 2005. Since 1995, the Republicans have held majorities in the House of Representatives and in the Senate, except for brief periods of Democratic Party majority in the Senate from January 3-20, 2001 and from June 6, 2001 to November 12, 2002.
""Government growing beyond our consent had become a lumbering giant, slamming shut the gates of opportunity, threatening to crush the very roots of our freedom. What brought America back? The American people brought us back -- with quiet courage and common sense; with undying faith that in this nation under God the future will be ours, for the future belongs to the free." Ronald Reagan (State of the Union Address 2/4/86)