European leaders scrambled to congratulate Francois Hollande following the French socialist party leader's victory in the country's presidential runoff on Sunday.

According to initial results published by the French interior ministry, Hollande won an estimated 51.05 percent of the votes, beating Sarkozy's 48.95 percent.

In a statement written in French, European Commission President Jose Manuel Barroso described Hollande as "a staunch defender of the euro and, with the support of partners such as the Commission, an architect of a new European economic governance."

"I listened to his (Hollande's) campaign and his ideas. We share the conviction that we must invest in growth and major infrastructure networks, mobilizing more strongly the European Investment Bank and the funds available in the EU budget, while staying on the course of fiscal consolidation and debt reduction," Barroso said.

"The challenges are many, for France as for the EU. I am convinced that together we have the ability to cope," he added.

Barroso said he can count on "the beliefs and personal commitment of Francois Hollande to advance European integration."

"There can be no strong Europe without France deeply engaged in Europe. Given the doubts expressed by some of our citizens about the changing world, a more united and stronger Europe is more than ever the right answer," concluded Barroso.

German Chancellor Angela Merkel, meanwhile, extended an invitation to Hollande in a phone call on Sunday night to visit Berlin as soon as he formally takes office in mid May, said Steffen Seibert, the spokesman of German chancellor office.

Both leaders reached consensus on the importance of forging ahead the German-Franco relations and vowed to bring forward even closer bilateral cooperation in the future, Seibert said.

German President Joachim Gauck also wished Hollande "good luck" during his five-year term for the service of France and Europe, a spokesman of the German President Office said.

The president said in a cable sent to Hollande that he was confident that Germany and France would further advance and intensify bilateral cooperation in the future.

Also on Sunday night, British Prime Minister David Cameron and Belgian Prime Minister Elio Di Rupo, all extended their congratulations to Hollande, while all vowing to work for a close partnership in the future.

"I look forward to good and close cooperation with Francois Hollande, not least in the effort to bring Europe out of the crisis and put more focus on job creation and growth," Danish Prime Minister Helle Thorning-Schmidt said in an official statement.

Denmark holds the ongoing EU Presidency, which runs till the end of June 2012. The Danish EU Presidency has put tackling the non-surrendering eurozone debt crisis, and boosting growth and employment in the 27-member bloc at the top of its agenda.