So what if he was? Was it within the President's power to abolish slavery? Lincoln repeatedly said it wasn't. Would Seward have said otherwise?
And there was no way Seward, or any other republican president, was going to just let the southern states go.
Don't be so sure. Seward was governor of New York. Let me acquaint you with New York's constitutional ratification statement.
That all power is originally vested in, and consequently derived from, the people, and that government is instituted by them for their common interest, protection, and security.That the enjoyment of life, liberty, and the pursuit of happiness, are essential rights, which every government ought to respect and preserve.
That the powers of government may be reassumed by the people whensoever it shall become necessary to their happiness;
It would be hard to argue that other states could not invoke the same power that New York had reserved for itself when it approved the constitution.
DiogenesLamp: "Don't be so sure.
Seward was governor of New York."
It's a problem which our Lost Causers exploit and encourage confusion on: they wish us to believe Civil War was over "secession", but it wasn't.
In fact, everyone in late 1860 and early 1861 acknowledged that Federal government had no authority to stop states from declaring secession, and no efforts were made to either stop secession or punish it.
The issue was whether Federal government could continue to enforce its laws in secession states -- i.e., tariffs.
Lincoln believed it could & should but Confederates took great umbrage at that.
So war began at Fort Sumter not over "secession" but rather over Lincoln's attempt to resupply US troops there.
What about Seward?
What would he have done about Fort Sumter?
The answer is that like other cabinet members Seward opposed resupplying Fort Sumter at first, but like the others came around to Lincoln's view eventually.
Had Seward been President, it's hard to guess what he might have done differently -- perhaps Seward the diplomat would have been more successful than Lincoln at negotiating the "fort for a state" deal with Virginia, who knows?
But the bottom line is Seward got along well with Lincoln, admired Lincoln and believed he, Seward, had a lot of influence over Lincoln.
So it's very likely the two were more of one mind than we might at first glance suspect.