Not the case in 1948. We had an arms embargo against Israel and 5 Arab nations involved. AIPAC didn't exist yet.
"Following World War I, the Balfour Declaration of November 2, 1917 was a product of efforts by President Woodrow Wilson at the urging of Supreme Court Justice Louis Brandeis. At that time, support for a Jewish state by the United States and American Jews was not popular.
Following World War II and the Holocaust, the United Nations General Assembly passed Resolution 181 on November 29, 1947, which devised a plan to partition the British mandate of Palestine. The Jewish community of Palestine accepted the plan, but the Arabs rejected it. Britain withdrew from mandatory Palestine on May 14, 1948, and Israel declared itself a State. Upon Israel's declaration of statehood, both the United States and the Soviet Union immediately recognized the state of Israel.
President Harry Truman, with the urging of his executive assistant, Clark Clifford, acted because he felt"it was the right thing to do." The Soviet motive was less altruistic. Because the government of Israel was controlled by the Labor Party, the Soviets believed Israel would become part of the Soviet Bloc and provide a Soviet entree into the Middle East. Israel chose the West and the Soviets were disappointed. The Soviets then courted favor with Arab countries and developed a hostile position to Israel.
Although the United States immediately recognized Israel, it also strictly enforced the Neutrality Act which prohibited the sale or transfer of any military weapons to Israel. The 1948 War of Independence established the state of Israel. No official assistance was provided by the United States. For the first 17 years of its existence, Israel did not receive any military or economic aid from the United States government. In 1948, individual U.S. citizens attempted to send arms to Israel in violation of the Neutrality Act. Some efforts were successful. Some efforts failed and individuals were prosecuted in federal courts. Some were treated sternly, and others were treated more sympathetically. (The first U.S. military weapons sold to Israel by the U.S. government were a few defensive Hawk antiaircraft missile batteries in 1964.)"
http://historynewsnetwork.org/article/751#sthash.n5i49Wpd.dpuf