(CNN) -- Zimbabwe's former finance minister Simba Makoni announced Tuesday he will try to unseat President Robert Mugabe in next month's election.
Simba Makoni announces at a Tuesday news conference he will challenge longtime President Robert Mugabe.
Makoni is a member of Mugabe's ruling ZANU-PF party and his announcement to run in the March 29 election presents a serious challenge to the longtime president.
Mugabe, who turns 84 this month, has been Zimbabwe's only ruler since it achieved independence from Britain 28 years ago.
Makoni made his announcement Tuesday in Zimbabwe's capital, Harare, to "clear the air of speculation and rumor," he told CNN.
He said he plans to release a campaign manifesto within the next 10 days.
While his campaign would mark the first public challenge to Mugabe's grip on power from within his own party, Makoni must get the support of heavyweights within ZANU-PF who believe it is time for a change if Makoni is to be successful. Watch why some are giving Makoni and outside chance of success »
Under Mugabe's rule, the once-prosperous Zimbabwe has suffered an economic crisis, with routine shortages of food, electricity and foreign currency.
Zimbabwe's latest inflation is estimated to exceed 24,000 percent, but economists say it is much higher.
While there is no official figure, unemployment among Zimbabweans is estimated at 80 percent. E-mail to a friend
CNN's Robyn Curnow and Kim Norgaard contributed to this report