Haaretz gives us this little bit of history in Israel and the US in the days leading to the declaration of statehood. It seems this was an extraordinarily difficult decision for the leaders of the Jewish community – the Yishuv – in Israel, with quite a few opposing but Ben Gurion in favor. Note also that the assessment of the heads of the Hagana, precursor of the IDF, was that there was a good chance the Jews would lose the war to the Arabs with their vastly larger and better equipped forces (reading that, revisionists like Morris and Shlaim must be shaking their heads sadly, oops they were wrong).
In the US, meanwhile, there was a great deal of opposition to the declaration and establishment of the state of Israel, and a strong suggestion to the Jews of the Yishuv to refrain from doing so. In the meantime, Harry Truman was being advised, primarily by the State Dept. (of course) not to recognize the state if it is declared. Clark Clifford was the only one who pushed for it.
Of course, Ben Gurion got his wish and declared the state. Truman then gave the go-ahead for the US to recognize the new Jewish state.