Elected as a Whig to the U.S. Senate in 1849, William Henry Seward, a former two-term governor of New York, quickly gained notoriety when, in his first significant speech on the Senate floor, he contended that the territorial expansion of slavery was contrary to the U.S. Constitution and “higher law.”  As a result, he was perceived by many as an antislavery radical.  In 1855, Seward was reelected to the Senate by a coalition of New York State legislators opposed to the Kansas-Nebraska Act of 1854.  Shortly thereafter, he became one of the key founders of the Republican Party, dedicated to opposing the expansion of slavery.

On October 25, 1858, while campaigning for Republican candidates in Rochester, New York, Senator Seward spoke of the “irrepressible conflict” between the free North and the slave South, which “means that the United States must and will … become either entirely a slave-holding nation or entirely a free-labor nation.”  Similar sentiments had been expressed by other Republicans, including a little-known senatorial candidate in Illinois, Abraham Lincoln, in his “House Divided” speech.  However, it was Seward’s oration that stirred controversy because of his public visibility as an influential senator and frontrunner for the Republican presidential nomination in 1860.  In the closing of his Rochester speech, Seward observed, “a revolution has begun” by which the American people were “gathering together the forces with which to recover” all that had been lost under the current Democratic administration of President James Buchanan. 

For his “Irrepressible Conflict” speech, Seward was vilified in the Democratic press as an “arch agitator” who was calling for armed federal intervention against slavery.  Some argued that the senator’s words fanned the flames of antislavery violence, such as previously perpetrated by radical abolitionist John Brown and his associates when they killed five pro-slavery men in Pottawatomie, Kansas, in 1856.  Further scorn was heaped upon Seward when Brown and his men raided the federal arsenal at Harper’s Ferry on October 16, 1859.  Convening three days after Brown and his co-conspirators were executed on December 2, members of the U.S. Congress spent weeks in heated debate over the issue of slavery.  Seward had been touring Europe from May until his return to the United States on December 28, but many Southerners considered John Brown’s raid to be the logical outcome of Seward’s rhetoric.  A newspaper in Richmond, Virginia, placed a $50,000 bounty on the head of the “traitor” Seward.

On February 29, 1860, Seward delivered his first major address on the Senate floor since returning.  He endorsed statehood for Kansas under a proposed antislavery constitution, but denounced John Brown’s “sedition and treason,” and claimed that, by contrast, his own vision of slavery’s end was peaceful, voluntary, and evolutionary.  The New York senator emphasized that the Republican Party did not seek to interfere with slavery in the South, but to stop its spread westward.   Whereas he had earlier alleged the incompatibility and “irrepressible conflict” between the slave South and free North, now he spoke of his hope for the peaceful coexistence of the two systems.  That speech and subsequent statements did little to reassure Southerners, angered some antislavery advocates, and made many view him as an unprincipled political opportunist.

On May 16 the Republican Party convened in Chicago, Illinois, for its second national convention.  Seward was still considered the favorite to win the presidential nomination, but he had several negatives.  His strong stance against nativism (the anti-immigrant movement) hurt his chances with Republicans who were former members of the nativist American (Know-Nothing) Party.  He would not be able to compete effectively in Border States (slave states in the Upper South) against native-son John Bell of Tennessee, the presidential nominee of the new Constitutional Union Party.  Furthermore, the likely Democratic nomination of Douglas called for a Republican candidate who could attract Western (i.e., Midwestern) voters.  The main obstacle, though, was the slavery issue.

Seward’s recent softening of his stance against the institution had not erased the memory of his “Higher Law” and “Irrepressible Conflict” speeches.  Although the Republican Party clearly opposed the expansion of slavery, many party leaders thought they could not win with a candidate considered too extreme on the issue.  The party needed to appeal to voters in states outside its New England and Upper-Midwest base—states like Illinois, Indiana, and Pennsylvania, which had voted Democratic in 1856 and in which slavery was not the paramount issue.  Tribune editor Horace Greeley privately stated the case:  “I want to succeed this time, yet I know the country is not anti-Slavery.  It will only swallow a little anti-slavery in a great deal of sweetening.  An anti-slavery man per se cannot be elected; but a tariff, river and harbor, Pacific railroad, free homestead man may succeed although he is anti-slavery.”  Despite his strong support of such policies as a Whig and then as a Republican senator, Seward did not fit the bill.

There were several other candidates, but the local favorite, former congressman Abraham Lincoln, seemed to have the most assets with no obvious negatives.  He had gained national recognition during the Lincoln-Douglas debates of 1858, but was still not well known outside of Illinois.  In December 1859, he published a campaign biography, and in February 1860, he delivered an address at Cooper Union in New York City which garnered positive press coverage and made him a sought-after speaker at Republican rallies throughout New England.  In May, the Illinois delegation entered the Republican National Convention unified behind Lincoln.  The convention’s location in Chicago gave the “rail-splitter” the home-field advantage and his campaign manager, David Davis, filled the hall with enthusiastic Lincoln supporters.  Lincoln’s advocacy of internal improvements and tariffs would make him popular in states like Pennsylvania and New Jersey, and he had managed to be anti-nativist and anti-slavery without alienating moderates.

Greeley initially backed Edward Bates, a former congressman from Missouri.  However, when Bates could not even carry his own state, the wily editor worked behind the scenes to convince anti-Seward delegates to switch to Lincoln, who had placed second to Seward on the first ballot.  When the Pennsylvania delegation moved into the Lincoln column on the second ballot, the Illinois favorite-son was within 3 ½ votes of the New York senator.  On the third ballot, four Ohio delegates switched to put Lincoln ahead, and others followed suit to give him the nomination.  The Republican platform opposed the expansion of slavery into the western territories without condemning the institution in the South, and denounced John Brown’s raid at Harper’s Ferry.

Governor Wise soon faded as a presidential possibility, but the Northern Democrats did nominate Senator Douglas.  The Southern Democrats, though, walked out of the convention to nominate their own presidential candidate, Vice President John Breckinridge of Kentucky.  The split in the Democratic Party, allowed the Republicans under Lincoln to win their first presidential election in November 1860.