The Taoiseach says Donald Trump does not have the skillset to help in Northern Ireland.
Leo Varadkar claims the US President's 'I win, you lose' tactics would not work in Stormont.
There has been no government there for almost a year now.
But the Taoiseach has read Trump's autobiography and thinks it rules him out.
He said: "While President Trump has many enormous talents and abilities, I don't think bringing about peace in Northern Ireland would be his skillset."
Mr Varadkar believes fresh elections or more meetings between the Irish and British government may be needed.
The Taoiseach says he would like to see a United Ireland but says it cannot be done without full agreement on all sides, Unionist and Republican.
According to Mr Varadkar, there cannot be a vote until there is a clear majority on both sides who actually want a united Ireland.
However, his own views are clear.
He said: "Our constitution is clear on this, our constitution aspires to there being a united Ireland and I share that aspiration but only on the basis it is done by consent."