The northern Democrats claimed a candidate selected from among themselves. The claim was allowed by their southern brethren, on condition of a satisfactory pledge against the Wilmot proviso. Four prominent northern Democrats entered the lists, to bid against each other for the votes of the slaveholders. General Cass's bid was accepted, and he was duly nominated, having declared the proviso unconstitutional.
Notwithstanding the hostility of the South to the pro- viso, they anticipated the possibility of being compelled to yield to the North, so far as to renew the Missouri compromise, and to consent to the exclusion of slavery north of 36° 30'—and here we find a solution of Mr.
Polk's rejection of the cession proposed by Mexico.
Great and valuable as Avas that cession, it was chiefly north of the compromise line, leaving sp'ace for scarcely more than two slave States. The territory offered was not far enough south to secure the object of the war, and hostiUties were to be continued for conquests, below the Missouri line.
In August, 1847, negotiations were opened for peace,