Who was in charge of Rome in 54 BC?

The Senate exercised political power in Rome, but this was basically controlled by Pompey Magnus in 54 BC, Caesar being absent in Britain (although 22,000 men is hardly 'the largest force embled to date') and Crus, the third Triumvir, was in the east invading Parthia.This left Pompey in political control, and he seized power outright in 52 BC, being appointed Consul by the Senate.