It had been feared that the populist coalition's proposals for a flat tax rate, allied to increased public spending, could a further explosion in see Italy's already soaring debt, breaking European Union rules.
"Membership of the euro is a fundamental choice for the future of our country and our young people", he said. "We'll see if we can start a discussion on the electoral law in parliament".
Last week, the spread of points between Italy's bonds and benchmark German bonds grew alarmingly, and Milan's stock market suffered losses as investors were spooked about the intentions of the populists.
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The pollster says it interviewed some 4,000 people and the survey had a margin of error of plus or minus 1.5 percentage points. The exit polls suggest that 77 percent of people in Dublin voted Yes - but so did 60 percent of people in the countryside.
The euro jumped on Monday and was set for its biggest one-day rise against the Swiss franc as a relief rally swept through currency markets after Italy's anti-establishment 5-Star and League parties abandoned plans to form a government.
Since the formation of the populist ruling coalition, Italian stocks have lost nearly 9%. Italy's stock market opened up 1.5 percent.
The leader of the Five Star Movement Luigi Di Maio has called for Mr Mattarella to be impeached.
"Although it would be disrespectful to Italians if this government doesn't get started because it's unpleasant to someone in Berlin or Brussels". "It's madness", said League chief Matteo Salvini, vowing to "bring democracy back to this country".
Separately, right-wing leader Matteo Salvini indicated in remarks to supporters Sunday that he had refused to submit to a presidential veto of his choice of a euroskeptic economy minister. He added that the League and 5-Star had refused to put forward any other name for the role.
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On Twitter, an inactive "pedbsktbll" account followed only 27 users, including two connected to people identified as Mr. Spokesmen for the C.I.A. and the Justice Department declined to comment.
A technical government will still be subject to votes of confidence in both houses of parliament, and the 5-Stars and League made clear Cottarelli wouldn't have their support. Such a call is usually a prelude to being offered a mandate to form a government.
The 5-Stars and the League together command just over half the lawmakers' seats.
The president didn't immediately announce his next move, which could include appointing a non-political premier to guide the country back to the polls after the inconclusive national election held March 4.
It's not the first time a president has rejected a ministerial nominee. The Democratic Party won about 20 percent of the vote.
On Monday, after receiving the mandate to try to form a government, Cottarelli said his primary job was to guide Italy to a new election. Mattarella's office declined to comment on the report.
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James finished with 26 points, 10 rebounds, and five assists but committed six turnovers and looked exhausted at times . The Cleveland Cavaliers are shooting 34.5 percent from beyond the arc and 75.8 percent from the free throw line.
Under that article, the president would be voted on "for high treason or attacking the constitution" by all members of parliament.