In Romans 11:23–24, Paul continues his arguments to prove that the Lord is not done with the nation of Israel. In this sermon on Romans 11:23–24 titled “Regrafting of the Jews,” Dr. Martyn Lloyd-Jones points out the three previous arguments in the beginning of the chapter for review and explains two more arguments in these verses. The first is based on the power of God; He is able to do anything. This means that the Lord is able to regraft the Jews back into His fold. Paul is continuing his illustration of the branches and roots of a tree. The Lord may have chosen to cut off the nation of Israel, but that does not mean that He cannot once again restore them. The second argument is in light of what God has done to the Gentiles. Because the Lord chose to bring salvation to the Gentiles, this is proof that He can also restore the Jews once again. Dr. Lloyd-Jones explains that it was even harder to graft in the Gentiles, so how much more would the Lord be willing and able to once again regraft His chosen people. As a final reminder, the Christian should always be aware that they are part of the branches that are growing and fruitful, lest they also are cut off.

http://www.mljtrust.org/sermons/regrafting-of-the-jews/