The idea of incorporating Texas into the United States has gained support both in Texas and in the United States Congress since Texas attained its independence from Mexico.

Definitive action on the measure has been delayed for several years, however, because of the divisive issue of admitting another slave state into the United States and the likely prospect that annexation would provoke a war with Mexico.

In early 1845, the United States Congress passes a resolution in favor of the annexation of Texas, which prompts Mexico to sever diplomatic relations with the United States.

The Mexican congress had never ratified Santa Anna's secret treaty with the Texans, and to underscore its opposition to Texas's independence, the Mexican congress passes a law that retroactively annuls any treaties signed by a Mexican negotiator while in captivity.