In the Regal era, a rex sacrorum (king of the sacred rites) supervised regal and state rites in conjunction with the king (rex) or in his absence, and announced the public festivals. He had little or no civil authority. With the abolition of monarchy, the collegial power and influence of the Republican pontifices increased. By the late Republican era, the flamines were supervised by the pontifical collegia. The rex sacrorum had become a relatively obscure priesthood with an entirely symbolic title: his religious duties still included the daily, ritual announcement of festivals and priestly duties within two or three of the latter but his most important priestly role – the supervision of the Vestals and their rites – fell to the more politically powerful and influential pontifex maximus.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What group's power increased after the rise of the Roman Republic?
Republican pontifices