The choice of Mr Philippe is aimed at drawing more defectors from The Republicans.
German Chancellor Angela Merkel may have broken with protocol to back Emmanuel Macron's candidacy.
Merkel's approach underlined her view that it was crucial not only for France, but for Germany, to help Macron succeed - a point that she has repeatedly stressed.
"There is a common conviction that we cannot only deal with Britain's exit (from the EU), but instead that we must above all think about how we can deepen the existing European Union and especially the euro zone". The two leaders left unsaid, however, what kind of treaty change they might seek.
Finance Minister Wolfgang Schaeuble warned that such deep-reaching reforms would require treaty changes, which were "not realistic" at a time when Europe is hit by a surge of anti-euro populism.
Taking over from outgoing prime minister Bernard Cazeneuve during a short ceremony, Philippe described himself as "a man of the right" who was driven by "the greater good".More news: Trading Statistics of Advanced Micro Devices, Inc. (AMD)
"In the past, the subject of treaty change was a French taboo".
A day after his inauguration, the fervently pro-EU Macron made his first trip overseas to Germany, the other half of the power couple driving European integration.
During their meeting, followed by a dinner in the German chancellery, outside of which people had gathered to cheer Macron, the German and French leaders also discussed issues like the posted workers directive, the reform of the European Union asylum system and reciprocity in trade.
And while his election was welcomed on the other side of the Rhine, many sectors of the German government and media are leery of the concessions Macron is expected to demand.
The German Chancellor, meanwhile, backed a relationship of "full confidence" that generates "close cooperation" for the well-being of both countries, and she emphasised that "the interests of Germany are closely linked with the interests of France".More news: US oil output back near records, challenging OPEC
"Macron clarified his position, saying he did not want Eurobonds or the mutualisation of (eurozone) debt" said Demesmay, referring to the pooling of funding and the build up of previous loans.
He also tried to show solidarity with Germany on the migrant crisis - an issue on which Merkel has pressed for European Union countries to work together - by saying that a common asylum policy was one area where Paris could cooperate with Berlin.
"We are sharing responsibility and we are conforming and Europe can be more unified on some of the other ingredients to the fiscal story than it has been prepared to deliver so far".
For far-right leader Marine Le Pen, Mr Macron's rival for the presidency, the selection of Mr Philippe reflects a continuation of the system she hoped to break.
Baroin reacted sharply to a suggestion that Macron, a 39-year-old ex-banker who served briefly as economy minister in a Socialist government, was reshaping politics.More news: Man who ran over pedestrians was 'hearing voices'
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