(someone) flock to (someone's) banner

Translations
(кто-то) стекается под знамёна (кого-то)
Many supporters flock to his banner during the campaign.
Многие сторонники стекались под его знамёна во время кампании.
Definitions
To join or support someone enthusiastically, especially by rallying to their cause, leadership, or group, often in large numbers.
Words
banner

noun
баннер
flock

verb
стекаться