The clash between the Thackeray cousins is getting uglier and more personal as the Lok Sabha election campaign gathers momentum. As the rivals battle it out for the Marathi vote, their family feud is spilling over into their rallies.

At a public meeting on Tuesday, Shiv Sena chief Uddhav Thackeray accused his cousin and Maharashtra Navnirman Sena chief Raj Thackeray of avoiding Bal Thackeray’s death anniversary. “Everyone, including [senior BJP leader] L.K. Advani and [NCP chief] Sharad Pawar came to pay tributes to Balasaheb, but you never came. Had you come, I would have let you sit next to me,” he said.

Mr. Uddhav Thackeray is Shiv Sena founder Bal Thackeray’s son. Mr. Raj Thackeray was once considered Bal Thackeray’s political heir, but was sidelined after Mr. Uddhav Thackeray took an active role in the party and went on to become his father’s successor. Mr. Raj Thackeray left the Shiv Sena and formed his own party in 2006.

The cousins face allegations of splitting the Marathi vote by not coming together. In the 2009 elections, Mr. Raj Thackeray’s party split the saffron vote in nine Lok Sabha constituencies, to the advantage of the Congress-NCP combine. Last month, BJP leader Nitin Gadkari made overtures to Mr. Raj Thackeray but backed off in the face of opposition from the Shiv Sena, a constituent of the BJP-led NDA.

Speaking at a rally in Pune on Monday, Mr. Raj Thackeray blamed Mr. Uddhav Thackeray for not allowing an alliance with his party. “Uddhav himself did not want to form an alliance with my party. Alliances are not formed through newspapers. If he phoned me, things would not have gone to this extent.”

Mr. Uddhav Thackeray shot back, saying: “People call us a regional party, but at least we are original.” He accused Mr. Raj Thackeray of being an agent of the Congress, acting on its behalf to split the Shiv Sena’s votes.

Mr. Raj Thackeray accused his cousin of hypocrisy in opposing Mr. Pawar’s entry into the NDA, even while asking for his help with Bal Thackeray’s memorial. “The Shiv Sena rules the Mumbai municipality but could not get a single plot for Balasaheb’s memorial. It had to approach Mr. Pawar. Isn’t meeting him a betrayal of Shiv Sainiks?” he asked.

Mr. Uddhav Thackeray pointed to Mr. Raj Thackeray’s parallel profession as a major builder in the city. “Everyone knows who is a builder here. Give me a single instance of selling land in Mumbai, and I will apologise. Had you come for Balasaheb’s death anniversary, you would have heard what I told Mr. Pawar.”