<P> Finally, there were the so - called Atlanticists . Ardently pro-Entente, they had strongly championed American intervention in the war since 1915 . Their primary political motivation was to both prepare the US for war with Germany and to forge an enduring military alliance with Great Britain . This group actively supported the Preparedness Movement and was strong among the Anglophile political establishment of the northeast, boasting such luminaries as former President Theodore Roosevelt, Major General Leonard Wood, prominent attorney and diplomat Joseph Hodges Choate, former Secretary of War Henry Stimson, journalist Walter Lippman and Senators Henry Cabot Lodge, Sr. of Massachusetts and Elihu Root of New York . </P> <P> A cosmopolitan group of upper and upper - middle class businessmen based in the largest cities took the lead in promoting military preparedness and in defining how far America could be pushed around before it would fight back . Many public figures hated war--Secretary of State William Jennings Bryan was the most prominent, and he resigned when he thought Wilson had become too bellicose . Grassroots opposition to American entry came especially from German and Irish elements . </P> <P> A surprising factor in the development of American public opinion was how little the political parties became involved . Wilson and the Democrats in 1916 campaigned on the slogan "He kept us out of war!", saying a Republican victory would mean war with both Mexico and Germany . His position probably was critical in winning the Western states . Charles Evans Hughes, the GOP candidate, insisted on downplaying the war issue . </P> <P> The Socialist party talked peace . Socialist rhetoric declared the European conflict to be "an imperialist war". It won 2% of the 1916 vote for Eugene V. Debs, blamed the war on capitalism and pledged total opposition . "A bayonet", its propaganda said, "was a weapon with a worker at each end". When war began, however, about half the Socialists, typified by Congressman Meyer London, supported the decision and sided with the pro-Allied efforts . The rest, led by Debs, remained ideological and die - hard opponents . Many socialists came under investigation from the Espionage Act of 1917 and many suspected of treason were arrested, including Debs . This would only increase the Socialist's anti-war groups in resentment toward the American government . </P>

3 reasons the united states entered world war 1