Many Hondurans oppose the return of the ousted Manuel Zelaya
Ousted Honduran President Manuel Zelaya should return home on Friday, according to a new plan for the country drawn up by mediator Oscar Arias.
The country's interim authorities, who removed Mr Zelaya, repeated that they would not reinstate him, but said they would give the new plan to Congress.
Mr Arias, who is also president of Costa Rica, was speaking during the latest round of mediation attempts.
He said the plan was the last he would present as mediator.
Two previous rounds of talks have failed.
"The clock is ticking fast, and it's ticking against the Honduran people," Mr Arias said.
"I warn you that that this plan is not perfect. Nothing in democracy is perfect."
If no agreement is reached, Mr Arias has suggested that the Organisation of American States (OAS) take over the negotiations.
That might put further pressure on the interim government, says the BBC's Steve Gibbs, who has been following developments from Mexico City.
The OAS, along with other international groupings, has been quite clear that Mr Zelaya is the legitimate president, and should be reinstated immediately.
'Talks have failed'
The crisis was triggered when Mr Zelaya sought to hold a non-binding public consultation to ask people whether they supported efforts to change the constitution.
Critics interpreted that as an attempt to remove the current one-term limit on serving as president.
The Supreme Court declared his attempt to hold a vote illegal under Honduras' constitution, before the military ousted Mr Zelaya from office and sent him into exile on 28 June.
Carlos Lopez, foreign minister in the military-backed interim government, told reporters in the Honduran capital, Tegucigalpa, on Wednesday that there was no chance of Mr Zelaya returning as president.
"This hypothesis of a possible return of Mr Zelaya to occupy the presidency is completely ruled out."
Officials from the interim government said before leaving for Costa Rica that they would submit Mr Arias' plan to Congress.
But since it was Congress that approved the ousting of Mr Zelaya, the move may prove to be of limited importance, our correspondent says.
Speaking in the Nicaraguan capital, Managua, Mr Zelaya said: "The coup leaders are totally refusing my reinstatement."
"By refusing to sign, [the talks] have failed."
Mr Zelaya has said he may try to return to Honduras as early as Thursday.
A previous attempt to fly back to the country was thwarted after the military blocked the runway at Tegucigalpa airport.
Mr Arias said there were several new proposals in his latest plan, including a truth commission to investigate events in the run up to Mr Zelaya's removal.
But correspondents say it is similar to his previous plan, which was rejected by the interim government.
It calls for Mr Zelaya to serve out his term, which ends in January. A power-sharing government would be set up by 27 July and presidential elections held a month early, on 28 October.
President Arias, a Nobel laureate, has warned of the dangers of a possible civil war in Honduras if talks fail, and has been urging both sides to continue negotiations.
"Neither side in this conflict will prevail," he said on Wednesday. "The victory will be halfway for both sides, or it will be for neither."
On Wednesday, supporters of Mr Zelaya and the interim president, Roberto Micheletti, staged rival demonstrations in Tegucigalpa.
Meanwhile, Venezuela has rejected a demand from the interim government to withdraw its diplomats from Tegucigalpa.
On Tuesday, the interim Honduran government accused Venezuelan President Hugo Chavez of interfering in the domestic affairs of Honduras.
Mr Chavez, an ally of Mr Zelaya, rejected the accusation.
Venezuela says the order to withdraw its diplomats comes from an illegal government. It says its relationship remains with the administration of Mr Zelaya.