The pro-Putin-style ralliers who assembled in front of Parliament to support PM Boyko Borisov as it the house voted on his resignation have reached 7,000, according to police data.
News agencies give much lower but still significant estimates, quoting numbers in the 2,000-3,000 range.
After the resignation was passed almost unanimously by Parliament, Borisov and his cabinet ministers walked out to be greeted by their supporters.
The resigned PM addressed the multitude, thanking them and calling them to use restraint, to refrain from all acts of provocation, and to quietly disperse.
Wednesday Borisov shockingly filed his resignation with Parliament in the wake of a string of massive anti-poverty protests that had started to turn violent.
However, many Bulgarians have expressed strong support for the resigned PM and his GERB party.
According to media sources and sources from the opposition parties, the pro-Borisov rally was not spontaneous, but rather orchestrated by the GERB party and institutions controlled by it.
Online media, such as Dnevnik.bg and Offnews.bg have written that some of the people present had been obviously organized by the companies or municipalities they work in.