All of the doctrines of grace (TULIP) are found textually throughout the Bible. The biggest ongoing debate over this topic is not whether God is sovereign, but whether God chooses us, or we choose God. Ephesians 1 makes it clear that God chose us before the foundation of the earth to be holy and blameless before Him. If man was required to choose God to be saved, no one would be saved because we simply DO NOT want God in our natural state. The main argument against predestination is free will. "God gave man free will to choose God, and God cannot violate man's free will." Let me ask you a question here. How Big is your God? If man has the right to resist the grace of the Almighty God, how big does that make God? You are literally elevating man above God by saying that man can decide whether or not he wants to be with God for eternity or not. That would be like a piece of clay deciding not to become a piece of pottery. The clay has no right over what the potter wills it to be molded into. The same principle goes with God. God is the Potter and we are His clay. We cannot decide whether we are going to heaven or not. It's entirely up to God. He created the Universe, therefore, He has the right to do whatever He wills to do.
You can find the idea of election being traced back throughout the Old Testament. Not to mention the fact that salvation is explicitly said to be designed in such a way so that no man can boast. Unconditional election is the only way that man has no boasting rights to his salvation. Not to mention that it's highly biblical (1 Corinthians 1:27-29 is the first passage that springs to mind).
The sovereignty of God regarding the salvation of sinners is through out the bible in both the old and new testaments. Paul makes this abundantly clear in not only Romans but in Ephesians, and other parts of the pauline corpus. And not only Paul but Christ does in the gospel of John.
Calvinists use Romans 9 to justify their beliefs, but it is grossly misinterpreted. To further the troubles of Calvinism, it was essentially a childish response to the five points of Arminism at the Synod of Dort, some fifty five years after John Calvin died. Calvin himself had nothing to do with the Five Points of Calvinism