From the Annals of Statehood –  In 1845, Texas voters approved annexation of Texas as a new member of the United States.  Voters also approved a new state constitution and the annexation ordinance. 

The annexation of Texas was part of a much larger political game between the free and slave states and between the pro-slavery Democrats and the anti-slavery Whigs.  In 1843, U.S. President John Tyler decided to pursue the annexation of Texas as part of his political platform for another four years in office.  Tyler claimed that he was attempting to  outmaneuver the British government’s alleged plans to recognize Texas as an independent state in exchange for emancipation of slaves.  Tyler believed this would undermine slavery in the US.  Through secret negotiations with Sam Houston’s administration, Tyler secured a treaty of annexation in April 1844.   Now in the public eye, the terms of annexation and Texas’ admission to the Union took center stage in the election of 1844. Pro-Texas-annexation southern Democratic delegates denied their anti-annexation leader Martin Van Buren of New York the nomination at their party’s convention in May 1844.  Instead, the Democrats nominated James K. Polk who ran on a pro-Texas Manifest Destiny platform.

In June 1844, the Senate, with its Whig majority rejected the Texas Annexation Treaty.  But Polk narrowly defeated anti-annexation Whig Henry Clay in the fall.   This opened the door for lame-duck Tyler to ask Congress to revisit Texas annexation which it did.  The last major act of the Tyler administration was to sign the Texas Annexation bill.