Zimbabwe’s opposition leader Morgan Tsvangirai delayed his return home on Saturday, after his Movement for Democratic Change (MDC) party said it had discovered an assassination plot against him, Reuters reports.

The opposition and political analysts claim mounting violence and intimidation, mainly targeting opposition supporters, make it virtually impossible for a planned June 27 presidential runoff to be credible.

“We have received information from a credible source concerning a planned assassination attempt against [party] president Tsvangirai. We are not in a position to say whether this threat concerns the actions of the state or a non-state actor,” spokesman George Sibotshiwe said, according to the Associated Press. “It has been decided that the (party) president will not return to Zimbabwe today,” he added. Sibotshiwe also mentioned party officials would consult their own security experts and regional leaders for advice and Tsvangirai would return “at the earliest opportunity.”

Repeated attempts in order to reach Zimbabwean authorities for comment were unsuccessful.

Tsvangirai planned to address a party caucus in Harare, Zimbabwe’s capital, on Saturday and a rally in Bulawayo on Sunday. Other party officials would lead those events, Sibotshiwe said.

Tsvangirai managed to survive three assassination attempts, including one in 1997 by unidentified assailants who tried to throw him from a 10th floor office window. MDC claims that more than 30 of its supporters and loyalists have been killed since the first round of voting March 29. It appears that the assaults are increasingly targeting the party’s top leaders.

Zimbabwe’s 84-year-old President Robert Mugabe ruled uninterrupted since the country’s independence in 1980. Currently, the former British colony is dealing with the world’s highest rate of inflation and an unemployment level that reached the 80 percent mark. Mugabe accused the E.U. for Zimbabwe’s economic collapse.