Why did president jimmy carter withdraw the salt it treaty from consideration by the senate in 1979

"Carter, the 39th United States president, sought to make the government "competent and compassionate but, in the midst of an economic crisis produced by rising energy prices and stagflation, met with difficulty in achieving its objectives. At the end of his administration, Carter had seen a substantial decrease in unemployment and a partial reduction of the deficit, but the recession ultimately continued. Carter created the United States Department of Education and United States Department of Energy, established a national energy policy and pursued civil service and social security reform. In foreign affairs, Carter strongly emphasized human rights throughout his career. He initiated the Camp David Accords, the Panama Canal Treaties and the second round of Strategic Arms Limitation Talks (SALT II). The final year of his presidential tenure was marked by several major crises, including the 1979 takeover of the American embassy in Iran and holding of hostages by Iranian students, an unsuccessful rescue attempt of the hostages, serious fuel shortages, and the Soviet invasion of Afghanistan."