Former Fisheries Minister Rajitha Senaratne says that the Sri Lankan opposition drew its inspiration from Narendra Modi’s campaign for prime minister in India, which tapped into a reservoir of frustration with the ruling Nehru-Gandhi family.

He said opposition campaigners had received advice from firms that worked on Mr. Modi’s campaign, although they had not received any funds from foreign governments.

“I think even India would like to have another government” in Sri Lanka, he said, “where they would have another understanding” with the country’s leaders.

Senaratne was among initial group of ministers and MPs to defect from the Sri Lanka Freedom Party (SLFP) with then General Secretary and now Common Candidate Maithripala Sirisena.

Since late November, just after the president called for elections, 15 ministers, deputy ministers and legislators have left the governing coalition.

Senaratne said a core group of party leaders had planned to defect in secret — swapping their telephones for ones they trusted not to be tapped, speaking in code and via group chats on Viber, a mobile app.

As soon as news of the defections went public, he said, the president “was talking to my wife every hour, trying to influence her.”

“It was painful for me, also, leaving a friend,” he was quoted as saying by the New York Times. “But he changed himself totally after the victory over terrorism. He was a wonderful person earlier. He used to listen to everyone.”

These days, he said, Mr. Rajapaksa is “trapped by his family.”