Sinn Fein has called on its supporters not to transfer to other candidates in the Meath East by-election after Fianna Fail asked for second preferences from the party.
Gerry Adams attempted to undermine their opponent's electoral plot by branding Fianna Fail part of a cosy political consensus alongside coalition parties Fine Gael and Labour.
"We are not advising our voters to transfer to Fianna Fail, Fine Gael or Labour," the Louth TD said.
"The very last thing that Meath East needs is another government backbencher or a return to the failed politics of Fianna Fail which have left this state with a legacy of bank debt, mortgage distress and unemployment.
"Fianna Fail created the economic and fiscal crisis. Fine Gael and Labour are now making things worse for struggling families."
With polling less than one week away, the main opposition party courted support from Sinn Fein voters and invited a raft of criticism from coalition Government parties Fine Gael and Labour.
Fianna Fail candidate Thomas Byrne has been asking Sinn Fein voters to transfer their vote to him but he has not advised his supporters how they should transfer their votes. It is believed to be one of the first times a Fianna Fail candidate has asked for transfers from the party, now their main rival in opposition.
Both Fianna Fail and Sinn Fein have been performing well in recent opinion polls, with the former government party picking up huge gains since their 2011 collapse.
Mr Byrne is favourite to battle it out with Fine Gael candidate and daughter of late TD Shane McEntee, Helen McEntee, for the Meath East seat.
Voters go to the polls for the single seat on March 27.