HARARE, Zimbabwe — A former ruling party loyalist who clashed with President Robert Mugabe over economic policy announced Tuesday he would run against Mugabe as an independent in next month's presidential election, hoping to galvanize others disillusioned with the party.

Victory in the March 29 vote has been seen as a foregone conclusion for Mugabe, 83, and the ruling ZANU-PF party against a weak and fractured opposition. So the challenge by former finance minister Simba Makoni, 57, gave the election a new dimension.

Officials of the smaller of two factions in the opposition Movement for Democratic Change said Arthur Mutambara, its leader, was giving his group's support to Makoni.

"Mugabe will be furious Makoni dared oppose him. This will have thrown the ZANU-PF house into disarray," said John Makumbe, a political scientist at the main Zimbabwe university.

"It's a fascinating split that has given a little ray of hope that Mugabe may not stay in power for ever," he said.

Makoni said at a news conference Tuesday that he decided to run after discussions with members of ZANU-PF and activists outside the party and that he had a lot of support.

"I am not an opposition party. I am not standing in the name of any party," he said. "I would like to stand as a candidate for ZANU-PF but I cannot."

Makoni said he would release his manifesto and election platform soon.

"I share the agony and anguish of all citizens over the extreme hardships we have all endured for nearly 10 years," he said. "I also share the widely held view that these hardships are a result of failure of national leadership."

Opponents blame Mugabe for an economic meltdown that has left Zimbabwe with the world's highest official inflation of 26,470 percent and acute shortages of gasoline, hard currency food and most basic goods. The collapse dates to 2000, when Mugabe ordered land in white hands be turned over to blacks, leading to violent takeovers and disruptions in farming, the lynchpin of the economy.