see nothing in the info you cited that supports your assertion that "it wasn't American foreign policy to support the establishment of a Jewish state," In fact, this excerpt contradicts your assertion:

"Meeting with President Truman in March 1948, Weizmann impressed upon the President the importance of establishing a Jewish state. This was undoubtedly one of the factors for the speedy recognition of the State of Israel by the United States."

Wanna try again?

If you are you saying that because a nation votes for a UN resolution and recognizes a state, that this qualifies as "supporting the establishment of a state", then you are correct. What I meant was more support then convincing an US President "at the last minute" to back a UN resolution.
[Btw: I wonder if are you going to say sometime in the future that France supported the overthrow of the Saddam regime and the establishment of a new Iraqi regime?
France voted for numerous resolutions against the Saddam regime. And France has vote for numerous resolutions supporting coalition efforts to establish a new regime. And no doubt that when Iraq has a elected Iraq govt, France will recognize this govt {which could survive as an entity for the next century or 1000 years}].
Now, I would say the key nations in the establishment of Jewish state, began with Royal Highness the Amir Faisal Arab Kingdom of Hejaz
Note: Article IV:
"All necessary measures shall be taken to encourage and stimulate immigration of Jews in Palestine on a large scale, and as quickly as possible to settle Jewish immigrants upon the land through closer settlement and intensive cultivation of the soil. In taking such measures the Arab peasant and tenant farmers shall be protected in their rights, and shall be assisted in forwarding their economic development."
In JUNE 28, 1919.
And the British govt starting with The Balfour Declaration, November 2, 1917. These particular decisions got the ball rolling so to speak.

Now, Truman wasn't at first favorable to voting for UN resolution, but he was persuaded by a close Jewish friend of his. This doesn't suggest to me that it's an US foreign policy which is supporting the establishment of a Jewish state as much as a President signing on to resolution which results in the legalizing of the "establishment of a state". Now, you may say this is nitpicking. But my point is for Truman this was relatively easy- he wasn't commiting the US to some strategic interest- though that did occur, but it was a decade or so later [as I said we did get dragged into it].
Now, Truman was interested in Turkey and Greece- he went to congress to get 400 million:
Truman Doctrine:
"I therefore ask the Congress to provide authority for assistance to Greece and Turkey in the amount of $400,000,000 for the period ending June 30, 1948. In requesting these funds, I have taken into consideration the maximum amount of relief assistance which would be furnished to Greece out of the $350,000,000 which I recently requested that the Congress authorize for the prevention of starvation and suffering in countries devastated by the war. "
http://www.yale.edu/lawweb/avalon/trudoc.htm