The 1864 National Union National Convention was the United States presidential nominating conventions of the National Union Party, which was a name adopted by the main faction of the Republican Party in a coalition with some War Democrats after Republicans nominated John Fremont over Lincoln.
The party name was created in May 1864, during the American Civil War, ahead of the 1864 presidential election, in which President Abraham Lincoln, then a Republican, was running for reelection.
The Radical Republicans, a hard-line faction within Lincoln's own party, held the belief that Lincoln was incompetent and therefore could not be re-elected and had already formed a party called the Radical Democracy Party, for which a few hundred delegates had convened in Cleveland, Ohio, on May 31, 1864. They eventually nominated John C. Frémont, who had been the Republicans' first presidential nominee during the 1856 election.
Republicans loyal to Lincoln created a new name for their party in convention at Baltimore, Maryland, during the first week in June 1864, in order to accommodate the War Democrats who supported the war and wished to separate themselves from the Copperheads. The convention dropped then-Vice President Hannibal Hamlin, a Radical Republican from the ticket, and chose War Democrat Andrew Johnson as Lincoln's running mate. The National Unionists hoped that the new party and the Lincoln-Johnson ticket would stress the national character of the war.
...called for pursuit of the war until the Confederacy surrendered unconditionally; a constitutional amendment for the abolition of slavery; aid to disabled Union veterans; continued European neutrality; enforcement of the Monroe Doctrine; encouragement of immigration; and construction of a transcontinental railroad. It also praised the use of black troops and Lincoln's management of the war.
On the first ballot, Missouri delegates cast their 22 votes for General Ulysses S. Grant. The Missourians quickly changed their votes to make Lincoln’s renomination unanimous.
Andrew Johnson, the former Senator from and current Military Governor of Tennessee, was named as Lincoln's running-mate. Others who were considered for the position, at one point or another, were former Senator Daniel Dickinson, Major General Benjamin Butler, Major General William Rosecrans, Joseph Holt, and former Treasury Secretary and Senator John Dix.
In keeping with the tradition of the time, Lincoln did not attend the convention. On hearing the news of his re-nomination, he wrote on June 9, 1864: