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What remained of the royalist army retreated, and while Juan de O’Donoju was cornered in the fortress of San Juan de Ulúa,[17] he hastily negotiated a treaty with Iturbide, called the Treaty of Córdoba.[14] Similar to the Plan de Iguala, this document guaranteed autonomy for New Spain within the Spanish Empire under the Bourbon dynasty. This successor state would invite Ferdinand VII to rule as emperor or, in default, his brother Don Carlos. If both refused, a suitable monarch would be searched for among the various European royal houses. In the meantime, a regency would replace the viceroy. All existing laws, including the 1812 Constitution, would remain in force until a new constitution for Mexico was written.[11]
Shortly after signing the Treaty of Córdoba, the Spanish government reneged.[17] Ferdinand VII had regained the upper hand against the liberals in Spain and increased his influence outside the country. He even had credible plans for the reconquest of the old colony. For these reasons, no European noble would accept the offer of a Mexican crown. Inside Mexico itself, there was no noble family that the populace would accept as royalty
So WI -- Both Ferdinand & Carlos decline - but due to problems in Spain -- can't keep other Houses from expressing interest.

?Any Ideas who would be available?
?What effect would this have on Mexico, and Europe?
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