The 1860 Republican victory was, in effect, engineered by Southern Fire Eaters, when they walked out of the 1860 majority Democrats' convention and formed their own minority party.
William C. Davis offers another interpretation in his book, The Deep Waters of the Proud, Volume 1, page 30-31. In particular he mentions two aspects of this of which I had not been aware - the nomination process at Baltimore and Douglas' actions after receiving the nomination of the Baltimore convention.
How exactly did Douglas get the nomination at Baltimore? First, his friends controlled the rules and procedures of the Baltimore convention. They refused to allow the return of two of the Southern delegations that withdrew at the Charleston convention. The Douglas backers then gave Douglas the nomination without the two thirds majority that the rules required.
People like Benjamin Butler of Massachusetts then worked in Baltimore with those who had walked out of the convention. Those Northerners supported Breckenridge to be nominated supposedly because Breckenridge was against secession even if Lincoln should be elected. It is true that the fire eaters you mention did think the Baltimore nominations would lead to secession and a Southern nation.
Breckinridge was reluctant to accept his own nomination. He saw the problem with it leading to Lincoln's election. Jefferson Davis and Robert Toombs met with Breckinridge and urged him to accept the nomination as it would put pressure on Douglas because it was obvious that Douglas could not win without the South. The only hope was that both Democrat nominees should withdraw so that a compromise candidate who would reunite the party could be chosen. Breckenridge agreed to accept his nomination with the objectives of the joint withdrawals of Douglas and Breckinridge, a reunited party, and a compromise nominee for the full party.
Davis met with Douglas to air this proposal. Douglas refused to withdraw his candidacy. Douglas' own ambition split the party and ensured Lincoln's election.
Fire Eaters had already split the party.
But Rusty, if you are hoping to convince me that historically Democrats are dishonest, underhanded and back-stabbing, I'm already sold -- don't need any convincing. ;-)
As to which one of those dirty-dealers was dirtier than the other, well, no way am I going to defend Democrats.
You may as well ask me about Obama versus Hill & Bill: one is the pot, the other kettles, as far as I'm concerned.
But... yes, no doubt that in 1860 Stephen Douglas felt "entitled" to the nomination, more-or-less the way a certain, ahem, candidate today runs as the "inevitable" choice.
Douglas had by far the most support and was willing to do whatever necessary.
That Southern Fire Eaters could not accept Douglas, and walked out of the April 1860 Charleston convention was their choice to split the party, and nominate their own candidate.
Whether Douglas could have, or should have stepped aside for a "compromise" candidate (and who might that be?), the split was initiated by Fire Eaters.
From my perspective, here's the key point: despite the split, the combined Democrat share of the popular vote increased from 45% in 1856, when they easily won electorally, to 48% in 1860, when they were defeated by the smaller Republican vote.
Further note that three normally Democrat slave-states, Virginia, Tennessee and Kentucky, went for the 4th party, the Constitutional Unionists.
Combined, 60% of Americans voted against Republicans in 1860, so that should have been and would have been an easy Democrat victory, had not the Southern Fire Eaters walked out of their Democrat convention.
The equivalent today would be one or more of the non-Romneys suddenly claiming they couldn't accept the party's nominee, walking out, forming their own party, nominating their own candidate, then demanding Romney step aside.
Regardless of what Romney did, any such actions would only guarantee Democrats' victory in November.
Greetings from Boston
Some of my Northern compatriots are beginning to expand, expound and excrete logical misrepresentations here