Complex sentence: After the breakup of the Whig Party in the 1850s, Bates became a Republican, and was one of the four main candidates for the party's 1860 presidential nomination receiving support from Horace Greeley who later switched to supporting Abraham Lincoln.
Split into simpler sentences: After the breakup of the Whig Party in the 1850s, Bates became a Republican, and was one of the four main candidates for the party's 1860 presidential nomination. He received support from Horace Greeley, who later switched to supporting Abraham Lincoln.