Good question. Lee certainly knew that. Perhaps the strategy was to cause large losses for the North and hold out until Lincoln lost the 1864 election because of those losses. Came close to working. I've read that until late that year Lincoln thought he might well lose in the fall. Lincoln even made Nevada a state before the election to help boost his chances. Nevada hardly qualified as a state at that point.
Lincoln didn't make anything a state, Congress does that. And Congress passed the enabling acts for three territories, Nebraska, Colorado, and Nevada, in March of 1864. If Lincoln was that worried about the results of the 1864 election then why didn't he 'create' the other two states as well?
Lincoln was actually convinced he would not be re-elected in November and even had his cabinet sign a promise that in the months between November and March (when McCllean would be inaugurated,) they would do all in their ability to win the final victory so that the Peace Democrats would not sign a treaty, splitting the nation in half. Sherman's taking Atlanta in September swung the public mood back in Lincoln's favor and along with McCllean breaking with the Copperheads after Atlanta fell and promising to continue the war which broke the back of the anti-war Democrat factions.