AS Sinn Féin reels from devastating losses in the local and European elections, senior TDs like Cork North Central’s Jonathan O’Brien will be under pressure to build the party back up in the coming months.

Across the country, the party lost half its local representatives and two of its three southern MEPs.

Mr O’Brien’s own backyard was no different.

Though Sinn Féin held its own in his north-west corner of the city, winning two seats, it lost two others across the northside, including party stalwart Mick Nugent, along with MEP Liadh Ní Riada.

However, Mr O’Brien believes the party can rebuild quickly if it takes the lessons of those losses seriously.

After a “sobering” internal review, he believes it’s time for Sinn Féin to return to focusing on working-class issues and exposing the “cosy consensus” between Fianna Fáil and Fine Gael.

Over the last 20 years — the last 10 in particular — Sinn Féin has grown from a fringe republican party to become the third-largest party with a much broader support base.

That’s why such a poor result in May was such a shock to the party.

“Obviously, it was a result we didn’t see coming,” said Mr O’Brien.

“I’d be lying if I said anything different. We weren’t picking it up on the doors.”

He said the party should have acted on some of the weaknesses picked up in a review of its under-performance in the presidential election last year, but won’t be making the same mistake twice if it implements the recommendations of a more thorough review following the recent elections.

Mr O’Brien dismissed the idea that Mary Lou McDonald, who replaced Gerry Adams as leader last year, isn’t up to the challenge.

“We all have to take responsibility, not just Mary Lou. Obviously, as party president, she bears that extra responsibility on her shoulders.

“I’ve had some private conversations with her and she took the election results very personally. But there seems to be this impression in the media and wider political circles that she is under pressure. That is not the case.

“No one is pointing the finger at her and saying: ‘this is your fault’.

“She’s not under any pressure internally. She is the right person for the job, and because you have a poor election result you don’t throw somebody under the bus.

“It wouldn’t have made a difference whether it was Gerry or Mary Lou or anybody else.

“This was coming. Things in politics come in cycles. We had a good day in 2014, so it was always going to be difficult to even match that, let alone increase on it, and we didn’t manage to do that. And we’ll learn from it.”

He said the party needs to work on organisation, communication, and making sure its voter base isn’t taken for granted.

“One of the key areas where we were always streets ahead of the other parties was our activism on the ground and our organisation.

“That wasn’t there. Our organisation has completely changed in the last 10 years. Our growth has been huge. We’re over 12,000 members now, and we sometimes look at 12,000 members on paper and think we have 12,000 activists willing to go out four, five, six nights a week.

“The type of political activist that is now joining the party has completely changed.”

Mr O’Brien said TDs like himself will be on the ground more often to try and rally the troops, with regular canvassing already taking place this summer.

Messaging was the other big weakness, he believes, as Sinn Féin-friendly voters failed to find a reason to turn out in May.

“I think we took them for granted. If you look at our election results over the last 20 years, we’ve always steadily built. We’ve always consolidated that build as we went along.

“In this election and the presidential election, a lot of our core vote that has come to us in the last 10, 15 years, didn’t come out.

“I don’t think it’s the case that they came out and voted for someone else — that might have happened in some cases, but I think most of them just stayed at home,” he said.

Though he believes the party has adopted the right policies, he says its emphasis in recent years took working-class voters for granted.

“I think we started broadcasting and appealing to middle Ireland, and focusing on them to try and increase our political strength, and our core vote felt a little left behind.

“We weren’t talking about the issues that are affecting them every day. The introduction of water charges, childcare, education, special needs. We started focusing more on issues like mortgages, the cost of household debt — which affects our core base as well, but our messaging was completely wrong.

“Some of the stuff that came up in the review is that we were being seen as angry, rather than radical,” he said. Part of that pivot in messaging will come from a reorganised front bench, where Mr O’Brien is moving from the public expenditure brief to transport, tourism and sport. That will give him plenty of local fodder, including issues around major transport projects like the Dunkettle Interchange and the North Ring Road, and a gaffe-prone Minister, Independent TD Shane Ross, to play against.

But it won’t just be Mr Ross in his sights. “I don’t think people realise how cosy Fine Gael and Fianna Fáil are within Leinster House,” he says. “They’re like lovers. They’re inseparable. Fine Gael can’t do anything without Fianna Fáil’s support. Fianna Fáil did a good job of playing at being in Opposition and Government at the same time, and we probably did a bad job of exposing that.

“But the gloves are off now. We have six months, probably at most, to a general election, and we have Fianna Fáil and Fine Gael in our sights. We will not be taking the foot off their necks for the next six months, and we will be exposing that cosy consensus,” he said.

He played down the prospects of Sinn Féin entering a similar Government arrangement.

“Personally, I couldn’t see any circumstances where we would agree a programme for Government with either Fianna Fáil or Fine Gael. Do I want to be in Government? Of course. Do I want to be in Government just for the sake of being in Government? No.

“Fianna Fáil? I wouldn’t trust them as far as I could throw them, and I wouldn’t even pick them up to throw them, to be honest.

“They have no red lines whatsoever. The only line they have is a finishing line, and that’s how many seats they can win in the next general election.”