The southern senators could have defeated the Morill tariff in the Senate. That's not what they all said in 1860 and 1861 when the bill was up for debate. That means it is an invention of your own.
They had done it before.
Yeah, when they had the votes to do so and the president to support them. They had neither the votes nor the president in 1861.
They could have worked out a tariff compromise in the Senate.
Not when the guys they would have been compromising with had enough votes and backing from the president to procede with whatever they wanted anyway.
Then why did none of their compromise proposals address the tariff if that was such a bone of contention? Jefferson Davis, Robert Toombs and Thomas Hindman all floated their own compromises. Tariffs did not figure in a single one of them, wasn't even mentioned. Thomas Letcher detailed 6 conditions that had to be met to avoid Virginia secession. Not one of them concerned tariffs. If tariffs were the major sticking point then why didn't the southern senators address them? Why concentrate on the issue of slavery and slavery alone?