"Baladeva means who gives strength for spiritual advancement. Nāyam ātmā pravacanena labhyo (Kaṭha Upaniṣad 1.2.23), nāyam ātmā balahinena labhyaḥ. These are the Vedic injunction. So without Baladeva's or Nityānanda's grace, one cannot make advancement.
āra kabe nitāi-cānda karuṇā koribe
saṁsāra vāsanā mora kabe tuccha...
(Narottama dāsa Ṭhākura)
This is the grace of Nityānanda Prabhu. Narottama dāsa Ṭhākura explains, āra kabe nitāi-cānda, karuṇā koribe. Narottama dāsa Ṭhākura is aspiring for the day when Nityānanda Prabhu will be pleased upon him. Just like Jagāi-Mādhāi was delivered by the mercy of Śrī Nityānanda Prabhu, so we have to pray Nityānanda Prabhu. He's very merciful. He's so kind, Baladeva, He gives spiritual strength. Then we can approach the Supreme Lord. Therefore we chant 'Nitāi-Gaura.' This is the process. We cannot change this policy. Pañca-tattva must be worshiped; otherwise wherefrom we shall get...?
The spiritual master... Nityānanda Prabhu is the spiritual master. Or spiritual master is the replica, representation, of Nityānanda Prabhu. So when Nityānanda Prabhu is pleased, then we become detached from this material attraction."
(Srila Prabhupada Lecture, Mayapur, March 4, 1974)