Micheál Martin and his party believe an election could be called before the budget and that Fine Gael would use Eighth Amendment legislation to try to damage Fianna Fáil during the campaign.

Fianna Fáil members were infuriated by Mr Varadkar’s comments, which cast doubt over their party’s willingness to renegotiate a confidence and supply deal.

A senior Fianna Fáil source said the Taoiseach is “gunning” for an election and his remarks were meant to “poke the sleeping bear”.

“Micheál has been taken aback by the dishonesty of the remarks,” the source said after Mr Varadkar suggested that Fianna Fáil are not committed to the confidence and supply deal.

He is being dishonest by saying Fianna Fáil are not agreeing to a budget. The doubts around the confidence and supply are premature and provocative.

Many in the party now believe Fine Gael are trying to create a rift which would give them the wriggle room to go to the country.

It is understood that Fine Gael has now pushed all of its selection conventions forward to be completed by this month, while Fianna Fáil is on standby to hold conventions at short notice.

Calling an election in the autumn would mean legislation to deal with the result of the referendum to repeal the Eighth could be delayed.

While Fine Gael were broadly supportive of the Eighth Amendment referendum, the issue caused a significant split within Fianna Fáil and could be used in an election campaign as the Taoiseach would argue his party is the only one which could guarantee speedy implementation of legislation.

It had always been intended to renegotiate the confidence and supply agreement after the third budget and Fianna Fáil members say the Taoiseach “suddenly wants to change the goalposts”.

“That can only be for one reason and that is to provoke an election, if he does that, on his own head be it. All of the instability is coming from the Taoiseach,” said a senior Fianna Fáil member.

Fianna Fáil TD Jim O’Callaghan said he was “surprised” the Taoiseach has suggested the renegotiation date be brought forward.

“Some people believe the Taoiseach is anxious to have an election in October,” he told RTÉ’s The Week in Politics.

“Maybe now, since we are not going to have a presidential election, he thinks it’s a suitable time to have a general election. I don’t agree with that. I know Micheál Martin doesn’t agree with that.

I know we have an agreement with Fine Gael. Leo was part of the negotiating team, which clearly says that, at the end of 2018, the parties will seek to review the agreement and see if it’s going to be renewed. That’s in black and white; there is no dispute as to when it should happen.

Relations between the two party leaders have deteriorated in recent times and it is understood the Taoiseach’s comments have only caused further anger.

Another senior party member said relations between Mr Martin and Mr Varadkar are “back to where we were in December”, when the country came to the brink of an election over the controversy surrounding former justice minister Frances Fitzgerald.

However, European Affairs Minister Helen McEntee said the Taoiseach and Mr Martin are in regular contact, although she said she “couldn’t tell” when both men last spoke.

Defending, Mr Varadkar’s remarks she said: “I think it’s fair enough to ask and to say before the agreement ends we talk about it. We are not planning an election, we don’t want an election.”

Meanwhile, Mr Varadkar has rejected claims that he has a credibility problem, having admitted he canvassed controversial TD Michael Lowry for support when he was about to become Taoiseach, reports Political Editor Daniel McConnell in New York.

In an interview with the Irish Mail on Sunday, Mr Lowry said Mr Varadkar rang him seeking his support in the Dáil.

Mr Varadkar said he contacted the subsequently convicted criminal for his vote but that no formal arrangement exists.

Asked if he had a credibility problem, he said: “First of all, I would point you to comments I have made in the Dáil consistently on this and not a briefing a spokesperson gave.”

When it was pointed out his spokesman, who speaks on his behalf, insisted no arrangement was in place, Mr Varadkar said sharply: “I speak on my behalf.”