The Renua leader Lucinda Creighton has promised to be a watchdog in government, and says a "grand coalition" of Fine Gael and Fianna Fáil would lead to a "crony bonanza".
Ms Creighton has admitted Friday's election is make-or-break for her young party, but is still targeting a total of 10 seats.
This morning she has launched a new advertising campaign promoting Renua as a watchdog in government.
She says voters should be scared of Fine Gael and Fianna Fáil working together without anyone else.
She said: "A Fianna Fáil and Fine Gael coalition would deliver a crony bonanza. Renua Ireland will be a fiscal watchdog to safeguard against a creeping return of bubble economics.
"We will stamp out crony politics."