A top official in President Robert Mugabe's party has rejected criticism from Zimbabwe Prime Minister Morgan Tsvangirai as "desperate".
The prime minister had accused the president of violating the constitution and their 2009 power-sharing deal.
But Jonathan Moyo told the BBC that Mr Tsvangirai was just "making noise".
The BBC's Karen Allen says the row is a clear attempt to ratchet up tensions ahead of polls due next year.
She says Mr Tsvangirai's attack on the Zimbabwean president was one of his strongest ever rebukes of Mr Mugabe.
At a news conference in Harare on Thursday Mr Tsvangirai said: "I have defended President Robert Mugabe at my own cost politically.
"But neither I nor the MDC can stand back any longer and just allow President Mugabe and the Zanu-PF to defy the law, to flaunt the constitution, and to act as if they own this country."
'Bread and butter issues'
Mr Tsvangirai said his Movement for Democratic Change (MDC) would not recognise any key appointments made by Mr Mugabe in the past 18 months, including governors, judges and envoys, saying they had been appointed unilaterally.
But Mr Moyo insisted that it remains the president's prerogative to choose provincial governors, saying they represent the president - not the prime minister - at local events.
He told the BBC's Network Africa programme that Mr Tsvangirai was "making noise" after a meeting with the leadership of his party, who gave him a hard time because they "wanted government jobs".
Mr Moyo, a former information minister who is on Zanu-PF's central committee, also dismissed suggestions that the deal was not working and said the unity government had delivered on "bread and butter" issues since it had been set up.
"This is a working arrangement that can last its full term," he said.
Mr Tsvangirai also recently complained about renewed violence at meetings to raise awareness about a new constitution.
Human Rights Watch has accused Zanu-PF supporters of being behind the attacks.
On Thursday, Mr Tsvangirai also accused the president of refusing to swear in white farmer Roy Bennett, the prime minister's choice for the post of deputy agriculture minister.
Mr Bennett was tried earlier this year on charges of plotting to oust Mr Mugabe and found not guilty.
"The matter of Roy Bennett has now become a personal vendetta and part of a racist agenda," Mr Tsvangirai said.
Long-time rivals Mr Mugabe and Mr Tsvangirai agreed to share power after violence marred the 2008 elections.
Under their coalition deal, the two politicians agreed to draw up a new constitution followed by a referendum, and then fresh elections.