The Third French Republic was NOT established until four years after the Franco-Prussian War ended because?

There was still hope by the traditionalists to put a royal heir on the throne, namely the Comte de Chambord, until the final failure occurred in october 1873. Marshall Mc Mahon was then elected President in november for a 7 years spell, which gave him the status of a "republican monarch". The Republic was founded in 1875. But the Republicans did not win the control of the new regime until the May 16th 1877 crisis when Mac Mahon dissolved the Parliament only to have a republican majority elected in the new Parliament.