Liberia's electoral commission has announced the start of campaigning for the country's second-round presidential elections, while Liberia's main opposition party is threatening to boycott the polls.

National Elections Commission Chairman James Fromayan said Tuesday that incumbent President Ellen Johnson Sirleaf and her main rival, Winston Tubman, will compete in a run-off vote on November 8.

But Tubman's party, the Congress of Democratic Change, has threatened to boycott the election, accusing Fromayan of being a Sirleaf supporter and saying that the first round of voting was rigged.

Fromayan told VOA on Wednesday that his commission has not received formal notification of a boycott by the CDC and that the election will proceed as scheduled.

Election officials said Tuesday that final results from the October 11 elections showed that none of the presidential candidates won an outright majority, sparking the run-off contest.

Officials say Mrs. Sirleaf won about 44 percent of the vote compared to about 33 percent garnered by former justice minister Tubman.

Former warlord Prince Johnson came in third with about 12 percent of the vote. He has said he would support Mrs. Sirleaf's re-election bid in exchange for a significant role in her government.

Observers from the U.S.-based Carter Center and the Economic Community of West African States have said the first round of voting was largely free and fair.