The new leader of Sinn Fein says she thinks Brexit and the struggle to restore power-sharing has created a polarisation in Northern Ireland.
Mary Lou McDonald was speaking after being officially elected as party leader at a special Ard Fheis in Dublin yesterday.
The Dublin Central TD is replacing Gerry Adams, who has stepped down as party president after more than 34 years.
Michelle O'Neill, the Sinn Féin leader in the North, has been elected as deputy leader.
The new leadership team faces a number of ongoing challenges, including dealing with the almost year-long struggle to restore power-sharing at Stormont.
In an interview with Sky News, Deputy McDonald expressed concern over a 'dangerous' level of polarisation in the North.
She said: "That's why I very much hope we get the institutions back up and running. The issues are clear, the issues are resolvable, there is nothing insurmountable.
"But if I'm truthful, they're only sustainable in the long-term when some people step into the light of the year 2018, in terms of same-sex marriage."
She insisted she 'can do business' with DUP leader Arlene Foster to restore the devolved government.
However, she also raised concerns that Brexit and the Good Friday Agreement are not compatible.
On the subject of Britain leaving the EU, she argued: "I sense a real resentment amongst Irish people that Ireland potentially becomes the collateral damage in a power-play within the Tories in London.
"Irish interests demand the entire Ireland stay inside the customs union and within the single market."
In her acceptance speech yesterday, Deputy McDonald called for a united Ireland - saying Ireland is no longer orange and green but a "rainbow of colours".
