Part of the problem with decoding just what happened on November 3, 2064 is that the sources are comically limited and contradictory.
For instance, in System Failure Major General Colloton states that President Pro-Tempore Gene Simone is acting as president until they find Vice President Daviar. Daviar is MIA, never to be seen again. Simone is presumably the president pro tempore of the UCAS Senate... no word on what happened to the Speaker of the House. It's never stated just who decided to make a two-star General the de facto head of the UCAS armed forces.
In Sixth World Almanac, Daviar is said to have survived an assassination attempt, been made "acting president", and announced marshal law. Presumably, Daviar is the one who places Brigadier General Colloton in charge before inexplicably disappearing at some point.
Finally, SR4A states that Daviar was made "President pro tem" and was the one that put (four star?) General Colloton in charge of the response. It doesn't mention Daviar disappearing, therefore implying she finished her/Haeffner's term.
In two out of three cases, someone clearly hands power to Colloton... she doesn't seize it, and she get's (as far as we know) honestly elected President four years later in 2068. As an aside, the SR4A history section is seemingly written by FastJack (as smart a runner as any) and clearly states Collton's election was the result of "learning from our mistakes". (i.e. a good thing.)
Off-topic note: three developers later and Shadowrun's canon hasn't gotten less maddeningly contradictory since Second Edition.