Congress MLA Hmingdailova Khiangte resigned from the membership of the Mizoram house on Monday becoming the fourth legislator of the ruling party to do so ahead of the November 28 state assembly poll.
With the resignation, the Congress' strength in the 40-member house has come down to 30, while that of opposition Mizo National Front (MNF) stands at 6. Four seats are vacant.
Mizoram is the only state in the north east under the Congress.
Khiangte submitted his resignation to Speaker Hiphei at his official residence, Assembly secretariat sources said.
When contacted Khiangte said that he would announce the reason behind his decision as well as the future course of action on Tuesday.
Resignations from the Congress began when R Lalziriliana, the state home minister and second-in-command of Chief Minister Lal Thanhawla's council of ministers, stepped down as minister on September 14 protesting against the government's refusal to create a separate Saitual district comprising his home turf Tawi seat.
Lalzirliana was expelled from the post of vice-president of the Mizoram Pradesh Congress Committee (MPCC) and the primary membership of the party on September 17.
He resigned from the party on October 12 and joined the opposition Mizo National Front on October 15.
Former health minister Lalrinliana Sailo had resigned from the state assembly on October 3 and also stepped down as the member of the All India Congress Committee (AICC), general secretary of the state Congress committee and primary member of the ruling party on the same day. He later joined the MNF.
Founded by legendary Mizo leader Laldenga in 1959, MNF is being headed by former chief minister Zoramthanga. The party is a member of the North East Democratic Alliance (NEDA) headed by the Bharatiya Janata Party (BJP).
Another Congress legislator Buddha Dhan Chakma, who was the former fisheries minister had resigned from the state legislature on October 16 and had joined the BJP in the presence of the visiting party chief Amit Shah the next day.