with Mexico. This position cost Van Buren the support of southern and expansionist Democrats; as a result, he failed to win the nomination. The delegates likewise could not settle on Lewis Cass, the former Secretary of War, whose credentials also included past service as a U.S. minister to France. On the eighth ballot, the historian George Bancroft, a delegate from Massachusetts, proposed former House Speaker James K. Polk as a compromise candidate. Polk argued that Texas and Oregon had always belonged to the United States by right. He called for "the immediate re-annexation of Texas" and for the "re-occupation" of the disputed Oregon territory. On the next roll call, the convention unanimously accepted Polk, who became the first dark horse, or little-known, presidential candidate. The delegates selected Senator Silas Wright of New York for Vice President, but Wright, an admirer of Van Buren, declined the nomination to become the first person to decline a vice presidential nomination. The Democrats then nominated George M. Dallas, a Pennsylvania lawyer. Martin Van Buren's Hammet letter Van Buren realized that accommodating slavery expansionists in the South would open the Northern Democrats to charges of appeasement to the Slave power from the strongly anti-annexation Northern Whigs and some Democrats. He crafted an emphatically anti-Texas position that temporized with expansionist southern Democrats, laying out a highly conditional scenario that delayed Texas annexation indefinitely. In the Hammett Letter, published April 27, 1844 (penned April 20), he counseled his party to reject Texas under a Tyler administration. Furthermore, annexation of Texas as a territory would proceed, tentatively, under a Van Buren administration, only when the American public had been consulted on the matter and Mexico's cooperation had been pursued to avoid an unnecessary war. A military option might be advanced if a groundswell of popular support arose for Texas, certified with a congressional mandate. In these respects, Martin Van Buren differed from Henry Clay, who would never tolerate annexation without Mexico's assent. With the publication of Clay's Raleigh Letter and Van Buren's Hammett Letter, Van Burenite Democrats hoped that their candidate's posture on Texas would leave southern pro-annexationists with exactly one choice for president: Martin Van Buren. In this, they misjudged the political situation. Tyler and the southern pro-annexationists posed a potentially far greater threat than Clay, in that the Tyler-Calhoun treaty would put immense pressure on the northern Democrats to comply with southern Democrats' demands for Texas.