Wiktionary
charm offensive
n. a campaign of deliberately using charm and flattery in order to achieve some goal, especially in a political or diplomatic field.
Usage examples of "charm offensive".
He launched himself on a desperate and incoherent charm offensive.
Many had gone on a charm offensive, and all but pushed pretty faces at him every time he appeared in public.
Under that tan he is blushing, which makes me think that beyond the slick charm offensive he must be a decent guy.
Nina tried to blunt the inevitable charm offensive she knew was coming.
While I was making these points in a speech to Japanese students at Waseda University, Hillary went on her own charm offensive in Japan, finding an especially warm reception among the increasingly large number of young, well-educated working women.