Explanation:
Following Texas’ successful war of independence against Mexico in 1836, President Martin van Buren refrained from annexing Texas after the Mexicans threatened war. Accordingly, while the United States extended diplomatic recognition to Texas, it took no further action concerning annexation until 1844, when President John Tyler restarted negotiations with the Republic of Texas. His efforts culminated on April 12 in a Treaty of Annexation, an event that caused Mexico to sever diplomatic relations with United States. Tyler, however, lacked the votes in the Senate to ratify the treaty, and it was defeated by a wide margin in June. Shortly before he left office, Tyler tried again, this time through a joint resolution of both houses of Congress. With the support of President-elect Polk, Tyler managed to get the joint resolution passed on March 1, 1845, and Texas was admitted into the United States on December 29.
