They call themselves the Sardines because of the crowds that have packed themselves tightly like the fish into squares across Italy.
Italy's "Sardines", tens of thousands of protesters against the right-wing party of former Interior Minister Matteo Salvini, have gathered in Rome for what is billed as their biggest rally yet.
The protest began a month ago as a flash mob in the northern city of Bologna against Mr Salvini, the leader of the League party, who aims to win a regional election there next month.
It has now become a movement against the League's anti-immigrant policies: a popular uprising against populism, the BBC's Mark Lowen reports.
There are no political flags at the rallies, just images of sardines and recitals of the anti-fascist song Bella Ciao.
The Sardines have shaken Mr Salvini and surprised Italy by how fast they have grown.
If Mr Salvini were to triumph there, it could spark a national election that polls suggest he would win.
They have given momentum to those trying to stop Mr Salvini winning the regional election in the north.
Organisers hope Saturday's event will be the biggest showing of the Sardines yet.
Mr Salvini crashed out of the coalition government earlier this year but his party remains one of Italy's biggest.
