Francois Hollande has seen his approval rating double in the week after terror stalked the streets of Paris.
A IFOP-Fiducial poll in December put the French president at 19 points, but a poll of 1,000 people on Saturday had him on 40 per cent.
The Independent's Paris correspondent John Lichfield says Hollande - regarded as France's most unpopular president ever - is "widely said to have responded faultlessly to the attacks".
Another poll showed 80 per cent of French people approved of the Socialist president's response to the attacks upon the offices of Charlie Hebdo and a kosher supermarket in which 17 people died.
Our correspondent writes Hollande was judged to have struck the right balance of "dignity, firmness and appeals not to blame the whole of France's Muslim population".
Such leaps in approval ratings are not without precedent in democracies. After the September 11 terror attacks, George W Bush saw his approval soar from 51 points to 86.
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