Ganden Tripa is literally translated as "The Throne-Holder of the Ganden or Gelugpa Tradition". Lama Tzongkhapa Himself is sometimes considered to be the first Ganden Tripa. The spiritual authority of the Ganden Tripas, hence, stemmed from the Founder of the Gelugpa Tradition itself.
The line of the Ganden Tripas passed down through a lineage of distinguished scholar-saints to the present Lobsang Nyima Rinpoche. The Dalai Lama lineage commences from Gendun Druppa, the first Dalai Lama, who was a young student of Lama Tzongkhapa. Lama Tzongkhapa predicted that the young Gendun Druppa will greatly benefit His Teachings and all sentient beings. Subsequently, the 5th Dalai Lama obtained political support and became the political head of Tibet. Nevertheless, all the Gaden Tripas are still the official spiritual Heads of the Gelugpa Tradition.
Ganden Tripas are sometimes the Teachers of both the Dalai and Panchen Lamas. In the absence of or during the minority of a Dalai Lama, Ganden Tripas are sometimes requested to act as Regents of Tibet, fulfilling both the spiritual and political role of a King of Dharma. For example, the late Ling Rinpoche – the 97th Ganden Tri Rinpoche - has acted both as a Regent in the 14th Dalai Lama's minority and as the Dalai Lama's Root Guru.
Out of respect for the Dalai Lama's political authority, Heads of other traditions in Tibet will usually obtain official recognition from a Dalai Lama or His Regent before actual assumption of their role. HH the present Sakya Trizin obtained teachings and official recognition as the Throne-Holder of the Sakya Tradition from HH the 14th Dalai Lama at the advice of the then Ganden Tri Rinpoche, Ling Rinpoche, while in Tibet.
HH the 100th Ganden Tri Rinpoche, Lobsang Nyima Rinpoche, was requested by HH the 14th Dalai Lama in 1995, to be the supreme Spiritual Head of the holy Gelugpa Tradition. Since then, His Holiness the Ganden Tri Rinpoche has served as the supreme Throne-Holder of Lama Tzongkhapa, untiringly working for the Dharma and all mother beings.
An article written by HH available on-line:-
Bodhicitta: attaining the highest bliss of Buddhahood that we may relieve all beings of their sufferings