
In alliance with pro-expansion northern Democratic colleagues, they secured the nomination of James K. Pro-Texas-annexation southern Democratic delegates denied their anti-annexation leader Martin Van Buren the nomination at their party's convention in May 1844. Senate for ratification, the details of the terms of annexation became public and the question of acquiring Texas took center stage in the presidential election of 1844. When the documents were submitted to the U.S. Through secret negotiations with the Houston administration, Tyler secured a treaty of annexation in April 1844. His official motivation was to outmaneuver suspected diplomatic efforts by the British government for emancipation of slaves in Texas, which would undermine slavery in the United States. President John Tyler, then unaligned with any political party, decided independently to pursue the annexation of Texas in a bid to gain a base of support for another four years in office. With Texas's economic fortunes declining by the early 1840s, the President of the Texas Republic, Sam Houston, arranged talks with Mexico to explore the possibility of securing official recognition of independence, with the United Kingdom mediating.

Moreover, they wished to avoid a war with Mexico, whose government refused to acknowledge the sovereignty of its rebellious northern province. political parties, the Democrats and the Whigs, opposed the introduction of Texas, a vast slave-holding region, into the volatile political climate of the pro- and anti-slavery sectional controversies in Congress. At the time, the vast majority of the Texian population favored the annexation of the Republic by the United States. It applied for annexation to the United States the same year, but was rejected by the Secretary of State.

The Republic of Texas declared independence from the Republic of Mexico on March 2, 1836.

Texas was admitted to the Union as the 28th state on December 29, 1845.

The Texas annexation was the 1845 annexation of the Republic of Texas into the United States of America. Boundaries of Texas after the annexation in 1845
