Quader said his brother HM Ershad handed him the chairmanship in accordance with the party's constitution and the support of its presidium.
He made the remarks at a media briefing in the party chairman's office in Dhaka's Banani.
Describing Raushon as a 'mother figure' to him, Quader hoped she would not do anything below her dignity.
In the presence of Raushon, Anisul Islam Mahmud, a member of Jatiya Party's presidium, said, "Raushon Ershad will perform the duties of party chairman. A council will called within six months to make a permanent appointment to the post through the democratic process."
Alleging that Quader became chairman in violation of the party's constitution, Anisul added, “Raushon Ershad will give GM Quader the honour of being co-chairman.”
Raushon acknowledged the leadership rift within the party and said, "There are concerns within the party. What is happening with the party? JaPa had been split in the past but is it happening again?"
"Hussein Muhammad Ershad worked so hard to build this party and now for the sake of the party, everyone must cast aside their issues and come together."
Addressing the ostensible leadership tussle, her brother-in-law Quader said, "Raushon Ershad is like a mother to me. She didn't proclaim herself as the chairman. I hope she won't do anything like that and tarnish her dignity."