So do I. Depending on the character of that war and whether we are perceived to be winning. Lincoln was convinced he couldn't be re-elected until the victories at Vicksburg/Gettysburg, followed by Sherman's taking of Atlanta just before the election. Johnson made no effort to enlist public support for the Vietnam War, defaulting to a pro-communist media which crucified him. He became so unpopular he didn't even bother to run for re-election. Now we're engaged in a diffuse, unconventional war that is likely to be protracted over a period of decades. This is a much more difficult sell, especially with the media doing everything possible to lend support to the enemy, at times practically denying that there even is an enemy. Sherman considered reporters no better than enemy spies and sometimes treated them as such.
Because Grant's casualties in Virginia (mainly the Wilderness Campaign) were so massive, Lincoln still expected to lose, notwithstanding the Gettysburg and Vicksburg victories.
The fall of Atlanta was decisive (along with the military vote).