[cnn-photo-caption image= http://i.cdn.turner.com/cnn/2008/images/06/24/art.obama.gi.jpg caption="Obama is reacting to the latest developments in Zimbabwe."] WASHINGTON (CNN) - Democratic presidential candidate Barack Obama said Tuesday that the Robert Mugabe government of Zimbabwe is "illegitimate and lacks any credibility," and said the United States should tighten sanctions against it.
Obama said he had spoken with opposition leader Morgan Tsvangirai, who has said he will not participate in a run-off election against Mugabe, scheduled for June 27, because of violence against him and his supporters.
"I have spoken with MDC Leader Morgan Tsvangirai to share my deep concern for the way his supporters are being targeted by the regime, and to express my admiration for his efforts to ensure that the will of the Zimbabwean people is finally respected," Obama said in a written statement.
"The Zimbabwean government's campaign of repression and brutality has made it impossible for the June 27 elections to be free and fair," Obama said, echoing a position taken by the United Nations on Monday.
He called for internationally monitored elections, and said if it proved impossible to bring them about, African and world powers should press for Mugabe to leave office.
"If fresh elections prove impossible, regional leaders backed by the international community should pursue an enforceable, negotiated political transition in Zimbabwe that would end repressive rule and enable genuine democracy to take root," he said.
Tsvangirai got more votes than Mugabe in a March 29 election, but failed to gather enough to avoid a runoff.
His decision to abandon his presidential campaign gives an apparent victory to Mugabe, who has been Zimbabwe's only leader since it gained independence from Britain in 1980. U.N. Secretary-General Ban Ki-moon and the head of the South African Development Community have called for Friday's vote to be postponed.
On Monday, the U.N. Security Council unanimously condemned the Zimbabwean government because of the violence that has continued in advance of the election runoff.