Complex sentence: Prime Minister Vajpayee's coalition government was on the verge of collapse because allied party leader Mamata Banerjee's quit but got majority support when the "no confidence" motion was passed by the opposition parties.
Split into simpler sentences: Prime Minister Vajpayee's coalition government was on the verge of collapse because allied party leader Mamata Banerjee quit. However, they got majority support when the "no confidence" motion was passed by the opposition parties.