My point is not neo-Confederates. Lincoln was justified in censoring the press during the war. The US often does this in war. The issue is a lot of cases fall into grey areas and aren’t always technically illegal. US laws are often vague and up to interpretation. Lincoln often arrested or censored people for expressing sympathy towards the south or peace. Many of them did support the south or had some other third party interest involved in the conflict. The issue is this isn’t always technically illegal to do in the US and can fall under freedom of speech. An American can express favorable views towards Iran and not be arrested. During a war that could change. That is the situation in the US. Lincoln was justified in what he did but if he loses the war those actions aren’t going to look as justified as otl. To many people it only proves those people he arrested points(in their minds). People are willing to accept a lot during war but only if you win it. If you lose they will call you out for every small thing afterwards. It’s going to be watergate or a bit worse. Not a execution(maybe a angry Union veteran shoots him but not a legal execution) but just a complete discrediting situation. He get impeached or steps down from office. How would a president who lost half the country not be considered a failure by most northerners? Also congress had a lot of republicans during that decision. Many of the non-republicans did not take that decision well. I imagine republicans lose most elections after the war and their political opponents during the war go after them hard. Whoever takes power after the war might claim a lot of stuff Lincoln and republicans did as self destructive and unamerican. It would be like people blaming Republicans and Hoover for the depression during the 30s but much more extreme.
The war could be lost by the Union in several ways.
* In 1860, the Confederate elect someone other than Jefferson Davis, who chooses not to attack Ft Sumter and keeps the South Carolina hotheads from doing so. Meanwhile, the Union elects someone other than Lincoln, who will choose to let the Confederates go.
* The Lincoln administration botches the Trent incident, leading to war with Britain, which allows the Confederacy to achieve independence.
* The Confederates select someone other than Jefferson Davis, who develops a cohesive (probably Fabian) strategy, drawing the war out. In 1864, the Democrats nominate a Peace Democrat, win the election, and acknowledge Confederate independence.
None of these wold result in Lincoln resigning. Only the second has any chance of Lincoln being impeached, and even that is unlikely. In any scenario where Lincoln is actually President, both he and the party will be able to blame the British or the Democrats for the loss. They may lose in the court of public opinion, but so could the Peace Democrats, or the Democrats as a whole. Between the Confederates all being nominally Democrats and the Copperheads, they could end up demonized as the party of traitors.
And while most of the population of the Union would be unhappy about losing the Confederate states, that's not the loss of half of everything, it's about 1/4 of US territory, 1/3 of US population and 1/10 of US industry.
Looking at attempted and successful assassinations, none were made because the President failed. They were a mix of complete loonies and people outraged that the President did not share their political extremism.