Some of the Romans had claimed the Genesis 12:3 promise to be blessed of God by blessing Israel.

Paul writes to the Romans, and in chapters 9, 10, and 11, he shows those Romans why Israel is no longer the way to God, as before when "salvation was of the Jews" (John 4:22).  

Paul tells them that God has a different gospel for them to be saved by.  

Then you can see Israel's actual blinding and casting away when Paul was inspired of God to recite to Israel, Isaiah's casting away curse from Isaiah 6:9-10.  

You can read that in Acts 28:25-29, and that is the end of Israel until the fulness of the Gentiles be come into what they are coming into, the body of Christ. (Hosea 1:9;  Romans 11:25-32;  1 Cor. 12:13;  1 Corinthians 15:1-4)  

Mike McGlathery