Prior to the 1864 election, which group was the main Northern opposition to Lincoln's presidency?

The correct choice is based on the context of the political landscape in the North during the Civil War. The Copperheads were a faction of the Democratic Party in the Northern United States that opposed the war and were critical of President Abraham Lincoln's administration. They advocated for an immediate peace settlement with the Confederacy, which placed them at odds with many in the North who supported continuing the war to preserve the Union.

During the 1864 election, the Copperheads actively campaigned against Lincoln's policies and sought to undermine his re-election efforts. Their opposition was significant enough to influence public sentiment in certain regions, as they appealed to those who were weary of the war and its consequences. This fervent anti-war stance characterized much of the Copperheads' activity and made them the primary opposition group at that time.

In contrast, the Radical Republicans were a faction within the Republican Party that supported a more aggressive approach to Reconstruction and civil rights for freed slaves. War Democrats were those who supported the war but were part of the Democratic Party, and the Liberty Party was a smaller group that focused on abolition prior to the Civil War. Thus, while other groups had their own platforms and impacts, the prominent opposition to Lincoln leading up to the 1864 election came primarily