During the agitation over the Wilmot Proviso, which would bar slavery from territory acquired from Mexico as a result of the Mexican War (1848), Yancey induced the Democratic State Convention of 1848 to adopt what was known as the "Alabama Platform". It declared that neither Congress nor the government of a territory had the right to interfere with slavery in a territory, that those who held opposite views were not Democrats, and that the Democrats of Alabama would not support a candidate for the presidency if he did not agree with them. This platform was endorsed by conventions in Florida and Virginia and by the legislatures of Georgia and Alabama.