Explain the crucial role of stephen a. douglas in the political events of the 1850s. why did douglas's attempts to keep the conflict over slavery

Stephen A. Douglas (1813 – 1861) was an American politician of the Democratic party, who lost the presidential election against Abraham Lincoln in 1860. He had been senator of the United States since 1858.

In the slavery matter, he defended the principle of popular sovereignty stating that each state should be able to decide (vote) on whether slavery should be allowed within its borders or not. In his debates against Lincoln he promoted the Freeport Doctrine, following the mentioned line of voting for the slavery issue, stating that each state should be able to rule out slavery if wishing so.

a. favoring native born americans over immigrants.