Fine Gael leader Leo Varadkar has said Sinn Féin's recent performance in the opinion polls is an opportunity to scrutinise their policies further and he described the parties tax policies as a "time bomb".

Speaking on Today with Sean O Rourke on RTÉ Radio, he said it was up to the National Broadcaster to decide if Mary Lou McDonald should be included in the Leaders debate tomorrow night. 

He described a Government with Fianna Fáil or Sinn Féin as the "double trouble option", and said if it happened, the economy would go into decline again.

On housing, Mr Varadkar said he couldn't justify that there are nearly 10,000 people without a home in Ireland, and said "it's stain on our society."

On health, Mr Varadkar said no party was saying they could build the National Children's Hospital at a cheaper cost.

He also admitted that Fine Gael TD Kate O'Connell was right when she said she was ashamed by the overcrowding in Crumlin Children's Hospital.

Mr Varadkar said opinion polls indicated that it was 'all to play for' in the election campaign and that Fine Gael could still make ground.

He said the party was getting a good response from the public and receiving broadly positive feedback.

Mr Varadkar said there had been a lot of comments about him in the course of the campaign, but that the campaign wasn't about him, it was about the voters.

The Fine Gael leader said his party's fair tax plan would help people with their bills, adding that they had proposals that would bring the country forward.

When asked about controversy surrounding a number of former Fine Gael TDs, including Dara Murphy and Maria Bailey, Mr Varadkar said none of those people were on the ticket, unlike Fianna Fáil candidates who were 'caught up in the Dáil voting controversy.'

He said that Fine Gael had listened to concerns about pensions and the party had put forward a number of proposals to address the problem. He said it would be the first legislation to be passed if Fine Gael leads the next government.

On housing, Mr Varadkar said his government had embarked on the biggest social housing building project in years and that we were finally beginning to see real progress and results.

He added that NGOs and charities had acknowledged that the reduced numbers of people in homeless accommodation was due to a stepping up in the provision of social housing.

Mr Varadkar said a number of investigations were underway into the case of a homeless man who was injured when his tent was removed by Dublin City Council.

He said the man, who was seriously injured, remains in a stable condition in hospital, and a housing plan is being put in place for him.

The Fine Gael leader said it was just two years since his party had balanced the books and once the party was in a position to invest in health, infrastructure and housing, it did so.

Leo Varadkar said his objective was for Fine Gael to emerge as the largest party after the election and his preference would be to form a coalition with other parties, like Labour and the Greens, but if this was not possible, then he was open to a coalition with Fianna Fáil.

He said his government had made the country a more modern and compassionate place and he believed that Fianna Fáil would be less enthusiastic about social change in the future.