Zimbabwe's prime minister, Morgan Tsvangirai, has vowed to fight a unilateral decision by President Robert Mugabe to hold national elections on July 31.
Mr. Tsvangirai has accused his government coalition partner of acting "unconstitutionally." The prime minister says he cannot accept the date.
Mr. Tsvangirai commented on Thursday, shortly after Mr. Mugabe issued a presidential decree setting the election date, which complies with a constitutional court order that requires the country to hold elections by the end of July.
The constitutional court issued the ruling in May in response to a lawsuit from an activist who demanded Mr. Mugabe set an election date before parliament ends its term June 29.
Prime Minister Tsvangirai, however, has said he would not support any election date that comes before democratic reforms are enacted.
He vowed to take the matter to court.
"I will not accept a situation where Zimbabweans will yet again be railroaded and frog-marched to another illegitimate and violent election."
Zimbabwe's 2008 elections were marred by violence, most of it by supporters of Mr. Mugabe's ZANU-PF party. The unrest prompted the regional leaders with the Southern African Development Community to nullify Mr. Mugabe's election victory.
He formed a power-sharing government with Mr. Tsvangirai, at the behest of the SADC.
Mr. Tsvangarai has been seeking adjustments to electoral laws and other statues that affect freedom of expression and association, and the work of the news media.
He says the earliest the country could hold elections would be August 25.
Mr. Mugabe has ruled Zimbabwe since its independence from Britain in 1980. The 89-year-old president has said he intends to run again.