How so? President Lincoln had his rivals and enemies (including democrats) in his cabinet. As a matter of fact, his second Vice President (Andrew Johnson, who became President at his death) was a democrat. BTW, Lincoln did NOT run as a republican for his second term, but as the "Union Party" candidate.
Too many egos. They would never play well together. Whoever wins the office is better off bringing aboard people who are team players. People they can trust and rely on to carry out the president’s agenda. Some names might be all right but for the most part they all have political ambitions. You would see much undermining of policy and leaking to the press. Find a bunch of good worker bees. This list has too many queen bees. Or in a more political uncorrect way, too many chiefs and not enough indians.
Not quiet correct. The R party had a convention, nominated him, and also nominated the D as his running mate. They then simply renamed the party the 'union' party to get the pro-war Dems, as there were many.