Public opinion in the United States was enraged

Public opinion in the United States was enraged; war talk was common, and pro-German elements remained silent. The key issue was Germany's harsh refusal to allow passengers to leave on lifeboats, as required by international law. President Woodrow Wilson declined to declare war right away; his primary purpose was to negotiate an end to the war. On May 10, 1915, in Philadelphia, he stated: "There is such a thing as a man being too proud to fight. There is such a thing as a nation being so right that it does not need to convince others by force that it is right."

The subject was hotly contested within the US government in the weeks following the sinking, and communication was exchanged between the US and German governments. German Foreign Minister Von Jagow maintained that the Lusitania was a valid military target because she was described as an armed merchant cruiser, flew neutral flags, and was instructed to ram submarines — a clear violation of the Cruiser Rules.

Von Jagow also claimed that the Lusitania had carried munitions and Allied troops on prior excursions. Wilson insisted that the German government apologize for the sinking, recompense US victims, and agree not to repeat the mistake in the future. Wilson's failure to take more harsh measures disappointed the British. President Wilson was urged by Secretary of State William Jennings Bryan that "ships carrying contraband should be prohibited from carrying passengers ... [I]t would be like putting women and children in front of an army." Bryan resigned later because he believed the Wilson government was biased in ignoring British violations of international law, and that Wilson was pushing the United States into the war.