Satisfied by these developments, Tyler dropped out of the race in August and endorsed Polk for the presidency. Polk's narrow victory over Clay in the November election was seen by the Tyler administration as a mandate for completing the resolution. Tyler announced in his annual message to Congress that "a controlling majority of the people and a large majority of the states have declared in favor of immediate annexation".[159] On February 26, 1845, the joint resolution that Tyler, the lame-duck president, had strongly lobbied for, passed Congress.[160] The House approved a joint resolution offering annexation to Texas by a substantial margin, and the Senate approved it by a bare 27–25 majority. On his last day in office, March 3, 1845, Tyler signed the bill into law.[161][162] Immediately afterward, Mexico broke diplomatic relations with the U.S., mobilized for war, and would recognize Texas only if Texas remained independent.[162][160] But after some debate,[163] Texas accepted the terms and entered the union on December 29, 1845, as the 28th state.[164]

Post-presidency (1845–1862)
Tyler left Washington with the conviction that the newly inaugurated President Polk had the best interest of the nation.