Brian Cowen presented Barack Obama with a bowl of shamrock
US President Barack Obama has paid tribute to the leadership of Peter Robinson and Martin McGuinness.
He said the two men had taken tough decisions which have paid dividends in Northern Ireland.
The president was speaking after St Patrick's Day talks with the first and deputy ministers in the White House.
Meanwhile, US economic envoy Declan Kelly has confirmed a Northern Ireland investment conference will take place this Autumn in Washington.
President Obama said he wanted to "salute the First Minister Peter Robinson and the Deputy First Minister Martin McGuinness for their outstanding leadership".
He said he believed the best days were ahead and because of the tough steps that had been taken there were dividends.
Barack Obama hosted a St Patrick's Day lunch on Capitol Hill
He also paid tribute to the work of the British and Irish governments and said the US administration would do all it could to support the peace process.
"I've congratulated the taoiseach (Brian Cowen) and his government for the extraordinary work that they've engaged in, working with Gordon Brown and the British government as well as Secretary Hillary Clinton, in reaffirming the progress that's been made in Northern Ireland.
"We want to be as supportive as possible in advancing the Northern Ireland peace process," he said.
Earlier, SDLP leader Margaret Ritchie said she was disappointed the leaders of all four of Northern Ireland's main parties were not at the private meeting with Mr Obama.
She and Ulster Unionist leader Sir Reg Empey were not invited.
Ms Ritchie said all four leaders appearing with the president would have sent out a strong image.
"I am told that it will not be possible to get that group together. I don't understand why that is not the case," she told a breakfast meeting in Washington to promote tourism in Northern Ireland.
Ms Ritchie later secured a last-minute meeting with the president.
As usual on St Patrick's Day, Ireland's prime minister Brian Cowen presented the president with a traditional bowl of Shamrock.
President Obama thanked Mr Cowen for his support on "critical" global issues.
Mr Cowen praised President Obama's sense of "mission" in the way he was positioning America around the world and praised the US leader's efforts since coming to office last year in repairing US banks and reviving the economy.
Earlier the taoiseach and his wife Mary, held a St Patrick's Day breakfast at the residence of US Vice-President Joe Biden.