The Senate rejected it.
The senate felt the treaty would limit U.S. independence in world affairs.
US presidents Teddy Roosevelt and Woodrow Wilson were proactive in so-called presidential initiatives. Despite that, the US Senate was not about to let claim for foreign policy to slip out of their constitutional hands. The treaty powers of the US Senate were most evident with Wilson. He virtually ignored the Senate as Wilson negotiated the Treaty of Versailles. The Senate rejected the League of Nations and overall the Treaty of Versailles.
the senate would not sign the treaty due to the fact the u.s. would have to join the league of nations (before UN) Joining the league of nations could involve the U.S. in European affairs. The U.S. would become isolationists till WW2
When the United States Senate stalled over the acceptance of The Treaty of Versailles, Wilson became determined. He argued the points on a moral basis. The US did not sign.
Before Woodrow Wilson was elected to the US presidency he believed that the Senate should play an intimate role in helping the US president to handle treaties. His views were clear and strong. After he became the US president however, he changed his mind. As president Wilson decided to look at his past statements as perhaps being too one sided on the issue of Senate cooperation. When WW 1 ended he took on his role as a negotiator of the Versailles Treaty with no contact with the US Senate. Wilson would find out that the Senate would make all his labors to bring nothing as the Senate by a wide margin voted against the Versailles Treaty.
After the elections of 1918, US senate was dominated by Republicans. However, even the majority party was divided over the issue of Treaty of Versailles. Woodrow Wilson despite all his efforts could not muster required two third majority to ratify the treaty.
unconditional adherence of the us to the charter if the league of nations
The U.S. Senate refused Woodrow Wilson's wishes of having, The League of Nations.
The Senate would not sign of the Treaty of Versailles and so the US did not join the League of Nations.
American President, Woodrow Wilson, believed that the Treaty was too harsh. The 'Fourteen Points' he had drawn up (which were to be the foundations for a fair and just Treaty) were almost entirely omitted from the final Treaty, and Wilson believed that Germany - which had recently undergone revolution - needed to gain stability and establish its new government.
The Treaty of Versailles, 1919--
he wanted unconditional acceptance of the charter of the League of Nations.