From Embattled Rebel: Jefferson Davis as Commander in Chief, by James M. McPherson (Penguin, 2014), Kindle Loc. 2125-42:
The apparent stalemate in front of Atlanta compounded the sense of futility and failure that spread through the North in the summer of 1864. Grant had bogged down before Petersburg and Richmond after the Army of the Potomac suffered sixty thousand casualties in two months with little to show for all the carnage. “Who shall revive the withered hopes that bloomed at the beginning of Grant’s campaign?” asked a New York newspaper on July 12.
Northern war weariness revived the prospects of Copperhead Democrats, who hoped to nominate a peace candidate for president and defeat Lincoln’s reelection. A clamor for negotiations with the Confederacy became insistent. Lincoln had no faith in such a parley. He was running for reelection on a platform calling for “unconditional surrender” by the Confederacy and an amendment to the Constitution to abolish slavery in a restored Union. But the United States president could not ignore the pressure for peace. When Confederate agents in Canada convinced New York Tribune editor Horace Greeley that they were empowered to open negotiations, Greeley in turn pressed Lincoln to respond. He did so, specifying Union and emancipation as preconditions for any such negotiations. This proviso gave Confederates a propaganda victory by enabling them to accuse Lincoln of sabotaging the chance for peace by laying down conditions he knew were unacceptable to the Confederacy. So long as the war seemed to be going badly for the North—as it did in July and August 1864—this impression dimmed the prospects for Lincoln’s reelection.
Jefferson Davis had no more faith that negotiations could achieve peace with independence for the Confederacy than Lincoln believed they could achieve peace with reunion. But while Davis did not have to face a reelection campaign, he too was subject to pressure from Southerners who longed for peace. Vice President Alexander Stephens led an informal coalition that urged Davis to cultivate Northern Peace Democrats by agreeing to negotiations without insisting on Confederate independence as a precondition. Davis rejected this approach. Since independence would be an ultimate goal of negotiations, he maintained, it would be dishonest and useless to pretend otherwise.