The passage of the Kansas-Nebraska Act made clear to the North that the South would accept no limitations for slavery. The position of the Southern leaders, in which they had the substantial backing of their constituents, was that slaves were property and that the Constitution, having guaranteed the protection of property to all the citizens of the commonwealth, a slaveholder was deprived of his constitutional rights as a citizen if his control of this portion of his property was in any way interfered with or restricted. The argument in behalf of this extreme Southern claim had been shaped most eloquently and most forcibly by John C. Calhoun during the years between 1830 and 1850. The Calhoun opinion was represented a few years later in the Presidential candidacy of John C. Breckinridge. The contention of the more extreme of the Northern opponents of slavery voters, whose spokesmen were William Lloyd Garrison, Wendell Phillips, James G. Birney, Owen Lovejoy, and others, was that the Constitution in so far as it recognised slavery (which it did only by implication) was a compact with evil. They held that the Fathers had been led into this compact unwittingly and without full realisation of the responsibilities that they were assuming for the perpetuation of a great wrong. They refused to accept the view that later generations of American citizens were to be bound for an indefinite period by this error of judgment on the part of the Fathers. They proposed to get rid of slavery, as an institution incompatible with the principles on which the Republic was founded. They pointed out that under the Declaration of Independence all men had an equal right to "life, liberty, and the pursuit of happiness," and that there was no limitation of this claim to men of white race. If it was not going to be possible to argue slavery out of existence, these men preferred to have the Union dissolved rather than to bring upon States like Massachusetts a share of the responsibility for the wrong done to mankind and to justice under the laws of South Carolina.