In my opinion, the main impact of the change in party alignments was to hasten the coming of the war by making compromise impossible.
The change I am referring to occurs when the Whig Party breaks up and eventually gives rise to the Free Soil and later the Republican Party.
Before this change, the Whig Party, like the Democratic Party, was a national party. Both parties were pretty strong in the North and the South. The Whigs broke up, however, largely along sectional lines -- the Northern and Southern Whigs could not continue to find common ground.
When this happened, the parties moved towards a North-South split. When Lincoln won his presidential election, he go no Southern votes. His party was a Northern party only. By that time, the Democrats had run a Northern and a Southern candidate as well.
So the parties realigned along North-South lines and that made compromise impossible.