The Free Soil Party was only in existence for six years, but in that short period of time, proved hugely influential in shaping the future contours of American politics. When the party was founded in 1848, the question of slavery and its expansion into the newly-won western territories was arguably the most important single political issue of the day. The country was deeply divided over the issue and the Free Soil Party was firmly on the side of those who opposed the extension of slavery.
The Free Soilers argued that the existence of slavery in the western territories would undercut the wages of white settlers who'd originally headed out West in search of a better life. It was no accident that the Party mainly attracted the support of those such as small farmers, petty tradesmen, and merchants, who stood to lose the most from competition with black labor, be it slave or free. The vast majority of Free Soil Party members and supporters were not, however, abolitionists. They opposed the extension of slavery primarily on economic, not moral grounds. An influx of free black workers would have been no more welcome to them than the presence of slaves.
Over the course of its brief existence, the Free Soil Party achieved only limited success at the polls, but its relatively small Congressional caucus was nonetheless able to exert considerable influence despite its modest size. As well as providing a temporary home for Democrats disillusioned with their party's stance on slavery, the Free Soil Party helped bring about a future realignment of American politics on the basis of the burning issue of the day.
In the aftermath of the Kansas-Nebraska Act remnants of the fading party combined with so-called "conscience" Whigs and anti-slavery Democrats to form the Republican Party. When the newly-formed party nominated John C. Frémont as its candidate for the presidency in 1856, it adapted the old Free Soil Party slogan as "Free Soil, Free Speech, Free Men, and Frémont." The Free Soil Party may have died, but its principles would live on in the party of Lincoln.