A senior former Fine Gael strategist says it's the party's "destiny" to end up in government with Fianna Fáil.

Frank Flannery says he thinks it's inevitable that the two right-wing parties will end up having to share power.

Mr Flannery - who resigned as a Fine Gael trustee in March - says the combined vote for the two parties isn't high enough for either to govern alone.

And speaking at the MacGill Summer School in Glenties, Mr Flannery says the two parties would have no issues getting together.

"It is the destiny of Fine Gael and Fianna Fáil, increasingly, to come together - whatever form that will take," he said.

"To stay in power and to exercise their power, I think the votes and the voters are telling the parties that that is what should happen - and they're also telling Labour and Sinn Féín to do likewise."

He also described Fine Gael's effort in the local elections - which was the first major campaign the party had fought since his departure - as one of the worst he'd ever seen. 

"The recent local elections - probably as an election campaign - was, my honest view, one of the worst I ever saw.

"We had the Seanad referendum - that was hardly a glorious effort for a party that actually brought it in as a significant and a major reform," he added.