Mr Gerry Adams and Mr David Trimble met yesterday for talks at Stormont against a background of heightened speculation that the British Prime Minister, Mr Tony Blair, could call fresh Assembly elections this autumn.
More talks between the two leaders are expected soon.
The Prime Minister's chief of staff, Mr Jonathan Powell, also held talks with Sinn Féin yesterday in central Belfast, and The Irish Times was told he met the Ulster Unionist leader in London earlier this week.
The talks were held in advance of the Taoiseach's meeting with Mr Blair tomorrow at Chequers, the British Prime Minister's official country residence
At the same time the Taoiseach has cast doubt on whether a fresh Assembly election can take place in the North this year, saying there are just four weeks left to name a date.
Despite some cautious optimism in the North about an early poll, Mr Ahern said there was not a plan "that we can feel confident we are going to implement". However, he stressed the Government was still working to try to achieve elections this year
On the eve of tomorrow's meeting with Mr Blair, Mr Ahern said while he was not conceding there would not be an early election, there were just a few weeks left to bring one about.
While the Government hoped to get to the position where an election date was named in the next few weeks, this would not happen at tomorrow's meeting.
"If there is no breakthrough the Government would have to look at what could be done in the new year," he said,.
In the North one well-paced source said this week's talks were facilitated by a "good mood" in political circles.
It is understood Sinn Féin's position is now being looked upon more positively by London, and that Mr Trimble, who is seen to be in a stronger position, is not set against the prospect of an autumn election.
His latest victory over party opponents at last weekend's Ulster Unionist Council has fostered qualified optimism, as has the efforts of politicians and others in achieving the most peaceful summer in years.
Both Mr Adams and Mr Trimble opted for a discreet approach after their meeting yesterday.
An Ulster Unionist statement placed the talks with Sinn Féin in the context of ongoing contacts among parties supportive of the Belfast Agreement.
A Sinn Féin spokesman took a similar line. "Sinn Féin will not be publicly rehearsing all the issues discussed by the two leaders.
"It is a matter of public knowledge that we are pressing for an election date as soon as possible. There is also a need to ensure that the institutions will be sustained and that outstanding aspects of the Good Friday agreement will be completed. "Unionists have concerns and all of this argues for a collective effort. "
Mr Mark Durkan, the SDLP leader, has called for round-table talks aimed at securing an agreed approach among parties which could pave the way to the restoration of devolution.
"There has not been a common text agreed since the Good Friday agreement, and it would send out an important signal if all pro-agreement parties could agree a common text on the joint declaration."