In a second tweet he said he thanked the PPP leadership for giving him a Senate seat. “As a political worker, I cherish my right to express my opinions on matters of public interest,” he wrote.

He said he will present his resignation to Senate chairman on Wednesday.

He also headed the Senate Standing Committee on Human Rights, and was known for his activism and interest in matters of human rights violations.

The Senator has been outspoken on many issues, often in contrast to party lines. Most recently, he came out in strong support of Azam Swati after the latter claimed that a compromising video of him and his wife had been recorded to blackmail him.

Even today, he had tweeted against parliamentarians’ phones being tapped. ‘We are as much part of the state as citizens as anyone else,’ he had written.

The senator had also stepped down as PPP Chairman Bilawal Bhutto Zardari’s spokesman last year.