God's call to those whom He has chosen is irresistible. That is, He calls everyone but knows which ones will respond. While it is tragic how most will not heed the irresistibility of God's beckoning, those of us who embrace His wooing can take great comfort in knowing He will never stop telling us to "come."
He who began a good work in you will complete it, beloved. There is no stopping God once we have become magnetized by His attraction. He will never leave us, nor forsake us, until we become totally His. What He promises, He fulfills.