The Republican Party, commonly referred to as the GOP, is one of the two major contemporary political parties in the United States, the other being its historic rival the Democratic Party. Founded by anti-slavery activists in 1854, the GOP dominated politics nationally and in most of the North for most of the period from 1860 to 1932. There have been 18 Republican presidents, the first being Abraham Lincoln, who served from 1861 until his assassination in 1865, and the most recent being George W. Bush, who served two full four-year terms 2001 to 2009. The most recent Republican presidential nominee was former Massachusetts governor Mitt Romney who lost in 2012. The party's platform is generally based upon American conservatism, in contrast to the contemporary American liberalism of the rival Democratic Party. The Republican Party's conservatism involves supporting free market capitalism, opposing regulation and labor unions, and supporting socially conservative policies. The party is generally split on the issue of how to deal with illegal immigration.