The Bush administration's Northern Ireland envoy is scheduled to take part in all-party talks later this month aimed at restoring devolved government.
Mr Mitchell Reiss will join the Taoiseach, Mr Ahern, and British Prime Minister Tony Blair in in the talks at Leeds Castle in Kent
"Reiss's presence is a sign of how serious theses talks are being taken," a US source said. "People are cautiously optimistic that a deal can be struck."
Northern Ireland Secretary Paul Murphy said yesterday the three-day talks would be the "moment of decision" for the peace process in Northern Ireland.
He said the "ingredients" were in place to reach an agreement on restoring devolved government. But he warned that intensive negotiations were not a staging post for further discussions.