The Liberian President, Ellen Johnson Sirleaf, says the second round of the presidential election will go ahead on Tuesday despite the withdrawal of her only challenger.
She urged Liberians to ignore a boycott demanded by her rival, Winston Tubman.
Mr Tubman, who polled 32.7% in the first round in October, said on Friday he would not take part in the run-off.
He was due to stand against Mrs Sirleaf, who won 43.9% of the vote.
He accused Mrs Sirleaf of trying to resurrect a one-party state.
"The election machinery is still flawed, as it was in the first round," he said.
But she accused him of violating the constitution, by urging people to give up their right to vote.
"Do not succumb to fear and intimidation. Do not allow any politician to hold our country hostage," Mrs Sirleaf said in a radio address to the nation.
"Do not allow Mr Tubman to falsely claim boycott, when what he is doing is forfeiting the rights of the finals because he fears defeat," she said.
'Refrain from violence'
Security was heightened in the capital, Monrovia, with joint United Nations and Liberian police convoys patrolling the streets at slow speeds with sirens on.
The UN, which maintains a 9,000-strong peacekeeping force in the country, issued a statement after the boycott call, asking Liberians to refrain from violence.
The US State Department said on Saturday it was disappointed by the decision of Mr Tubman's Congress for Democratic Change (CDC).
"The CDC's charge that the first-round election was fraudulent is unsubstantiated," State Department spokeswoman Victoria Nuland said in a statement.
International observers have also said the polls had been peaceful and transparent.
The West African regional body Ecowas has warned that a boycott risks destabilising Liberia and called on Mr Tubman not to pull out of the process.
The new head of Liberia's election commission, Elizabeth Nelson, said the presidential vote would go ahead as planned.
The former head of the election commission, James Fromayan, resigned last week after Mr Tubman's CDC complained it was biased.
But the party had said other checks and balances had to be put in place for Mr Tubman to take part in the vote.
Mrs Johnson Sirleaf.
She became Africa's first female elected head of state after the 2005 elections, following the end of Liberia's 14-year civil war in which 250,000 people were killed.
These are the first post-war elections organised by Liberians - the previous poll was run by the UN.
Mr Tubman is a former UN envoy and nephew of Liberia's longest-serving president. His running mate is former footballer George Weah, who was defeated by Mrs Sirleaf in the 2005 poll.
Former rebel leader Prince Johnson, who came third in the first round with 11.6%, has urged his supporters to back Mrs Sirleaf.