That is simply a fabrication and misrepresentation. In other words, a lot of BULL.
The Morrill Tariff passed the House with ease in May of 1860 despite virtually unanimous opposition by every southern member.
Senator Hunter exerted every bit of parliamentary strength he could to delay the vote in the Senate until after the election hoping for the slim chance that enough votes would emerge to block it.
They did not and had every single southern member stayed in the Senate and voted against the Morrill Tariff, the best case scenario they could have hoped for was a tie, in which case Vice President Hamlin would cast the deciding vote in favor.
Why stay in a union that was slowly strangling your ability to survive?
Yes it passed the House in May 10 1860. It did not pass the Senate until Feb 20 1861. After a conference committee with the house to iron out some minor differences the Senate passed the Morrell Tariff Act, March 2 1861
In the Senate 24 yes votes, 14 no votes and 12 abstentions.
5 of the abstentions were southern Democrats. Had the senators of the 7 seceding states remained in the Senate, that would have probably been 14 more no votes. The bill would have failed.
“Vice President Hamlin would cast the deciding vote in favor”
Until March 4 1861 John C. Breckenridge was the Vice President of the United States.