Northern Free-Soilers and Republicans had their differences. But one thing they agreed on was they both opposed slavery expanding to the territories. Both opposed the Southern planters who they called "slave oligarchs". Together they had an advantage over earlier attempts by political parties to oppose slavery. Earlier, Northern politicians had to go easy on slavery issues because they needed the political power of the Southerners to win national elections. For that reason they supported slaveholding presidents, congressmen and senators. But the Republicans and Free-Soilers did not need to please the Southern politicians and they attacked their power at every opportunity. They brought up old arguments that Slave Power had too long held power in American politics. That argument was used when Thomas Jefferson had been elected president. It came up when Missouri was admitted as a slave state in 1820 and again in 1845 when Texas was annexed. This time the Republicans hammered the idea hard. It hurt Northern Democrats the most. Republicans won many offices in the North that had been held by Democrats for decades. In the 1860 election, the Democrats split between North and South with each supporting their own candidate. This allowed Lincoln to win even though he did not have a majority. This ended the Slave Power dominance in politics and was a contributing factor to the American Civil War.