His illness has divided the MDC party, with officials publicly jockeying to succeed the former trade union leader.
Early Wednesday, Tsvangirai appointed Chamisa to take charge of both the party and coalition business and effectively undercutting Mudzuri "until the president returns".
This was after Mr Tsvangirai's spokesperson Mr Luke Tamborinyoka had released a statement purportedly from his boss appointing Mr Chamisa as the acting MDC-T president.
Tsvangirai in 2016 announced he had colon cancer and has come for treatment in the past. "VP Chamisa also continues in his assigned duties as the acting chairperson of the MDC Alliance".
There is chaos in the party as Chamisa and the two other vice presidents Thokozani Khupe and Elias Mudzuri are fighting over the control of the party and the MDC Alliance.
There are reports that Mr Chamisa's position has also been strengthened by the support he enjoys from MDC Alliance partners like Professor Welshman Ncube and Mr Tendai Biti.More news: Toby Alderweireld Starts - Tottenham Hotspur Team vs Newport Confirmed
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She posted on her twitter handle: "Three consecutive MDC-T congresses have elected yours truly as deputy President to president @mrtsvangirai & other officers primarily to avoid a leadership vacuum at such an eventuality, & to shut any that may be artificially created by those with hidden agendas".
Dr Khupe, perhaps in her first unambiguous stance, has declared that she is the rightful heir to Mr Tsvangirai's presidency.
Tsvangirai has led the MDC since its formation in 1999 and the party has posed the most formidable challenge to the ruling Zanu-PF party. The ruling party to be precise because they're are scared.
He and others in the MDC had said they were going into it to "save" the country because all hospitals, schools and supermarkets were either closed or empty as the Zanu-PF administration allowed hyper- inflation to wreck the economy.
This intense shuffling to land the MDC-T's top job has been ignited by wide speculation party leader Morgan Tsvangirai's deteriorating health could force him to step down as it becomes apparent he may fail to recover in time to contest elections slated for mid-year.