To complicate matters, Mr Paniagua's congressional majority depends on a group of slippery defectors, who have shuttled in and out of the Fujimorist benches.
Congress's first act under Mr Paniagua's speakership was to reinstate three Constitutional Court judges sacked in 1997 for ruling that Mr Fujimori could not stand for re-election this year.
The opposition wants Valentin Paniagua, a veteran democrat, to become the new speaker of Congress, since it sees him as a suitable caretaker president were Mr Fujimori to be ousted.