Frederick Barry from Canada wrote:
According to the Midrash, G-d went to all of the other nations before the Jews and offered them the Torah and they refused. If so, then why are we called the chosen nation? It seems like all of the others were chosen first, only they refused.
Dear Frederick Barry,
G-d already chose Jacob and his offspring long before the giving of the Torah. G-d told Jacob: "The Land which I gave to Abraham and to Isaac, to you shall I give it, and to your offspring after you." (Genesis 12) The Land was to be given to the Chosen People, as G-d said to Abraham, "I have given you and your seed after you the Land of your dwelling, the whole Land of Canaan as an everlasting possession, and I will be their G-d." Thus, we see that Jacob and his seed were chosen already as "G-d's people."
King David referred to this when he wrote: "For G-d chose Jacob, Israel as His treasure (Psalms 135:4)
Furthermore, G-d knew the other nations would decline; He only offered it to them so that they couldn't later claim that they never had a fair chance.