BENGALURU, July 26 (Reuters) - The chief minister of India"s Karnataka, the only state ruled by Prime Minister Narendra Modi"s party in the country"s prosperous south, resigned on Monday in the latest political shake-up in the Hindu nationalist group. B.S. Yediyurappa, a four-time chief minister of the state, home to India"s technology capital of Bengaluru, had helped the Bharatiya Janata Party (BJP) form its first government in India"s southern region in 2008. The party has failed to make inroads in other southern states despite running the country since 2014. Aside from Yediyurappa"s resignation, Modi recently dropped many senior ministers from his cabinet as he tries to reinvigorate his administration dented by a huge second surge in coronavirus infections. Yediyurappa, 78, quit because he was older than its cut-off age of 75 years for ministerial positions, BJP spokeswoman Malavika Avinash said. "I had no pressure from senior party leaders. I am voluntarily submitting my resignation," Yediyurappa said in an emotional address broadcast live on local television channels. Bengaluru hosts offices of big multinational companies such as Microsoft (MSFT.O), Amazon (AMZN.O) and Goldman Sachs (GS.N). Analysts said the BJP will have to move fast to name a successor or risk being outmanoeuvred by the opposition. "If the BJP cannot come up with a name soon enough, it would give the opposition a chance to swoop in," said Narendar Pani, dean, School of Social Sciences at the National Institute of Advanced Studies in Bengaluru. "The challenge for the BJP will be to find a successor who will have the same kind of pull and can bring various groups together." The BJP changed the chief minister of the northern state of Uttarakhand twice this year, months ahead of local elections. Karnataka elections are due only in 2023.