He was joined by a large number of partyworkers as he sat on dharna at the grave of his elder brother, slain JMM leader Nirmal Mahto at Uliyan, near here.
"I strongly oppose the trend in the party (JMM) to field candidates from outside it and even the state in the Rajya Sabha polls," Mahto, who has himself procured nomination papers for the polls, told newsmen.
The party was not willing to learn any lesson from its past mistakes, he said referring to the election of Supreme Court lawyer R K Anand and industrialist K D Singh, who had switched over to Congress and Trinamool Congress respectively within months of being elected to the Rajya Sanha on JMM tickets.
"It is also ridiculous for a party like JMM, which had struggled for decades for separate Jharkhand statehood, to put up outside candidates in the Rajya Sabha poll," he said.
Asked whether he would defy the party stand and contest the Rajya Sabha poll, Mahto said he would consult the JMM leadership and its MLAs before taking a final call.
He claimed that more than 6 out of the total 18 JMM MLAs were supporting his candidature in the May 3 polls and he would appeal to all the 81 MLAs in the state assembly to support him as he was a 'son of the soil'.