I'm sure this must have been done, but what if for some reason Seward takes the 1860 nomination- reconciliation with Greeley, better organisation, doesn't take the European tour but still manages not to put his foot in his mouth etc.
The argument made against him was that he was so radical the Republicans might lose Indiana, Illinois, Ohio, and/or new Jersey, the result being that Douglas might be able to get the election thrown to the House. Plasusibility?