Why do some write an "a" after the verb "convocar" and others omit it?

Question

The other day I was reading something that had a conjugated form of the verb "convocar" in it. (The exact phrase was convoca a los estados americanos.) Though I'm familiar with the word, I don't have occasion to use it much, so I decided to look it up to make sure I knew it well. In the process, I noticed that some put an "a" after this verb and others do not. In order to rule out that this "a" that appeared to be in usage wasn't simply the personal "a," I looked for a phrase that would help me eliminate that possibility. Via linguatools, I discovered that "convocar (a) elecciones" was a common collocation. So then, I went to Google's Ngram Viewer to see what it might reveal and it showed me this:

I took a very cursory look at some of the books for these two phrases and noticed that, in each case, both seem to be used transitively, both are in active voice, both are used by what appear to be books by native Spanish speakers, and both appear to share the same meaning. If you want to see for yourself, you can link to the Ngram above here.

Obviously, one is more frequently used than the other, and one — convocar a elecciones — appears to be slightly older than the other if Google's collection can be any sort of indicator. According to the Google Ngram, the variant with the "a" is in use at least by 1841 and the variant without it doesn't appear until 1863. Other than that, I don't see much of a difference, which then leads me to the question Is the "a" optional and in all registers? If it isn't optional, is there some slight nuance in meaning that I'm missing? How will I know when to use which?

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¿Por qué algunos escriben una "a" después del verbo "convocar" y otros la omiten?

El otro día estaba leyendo algo que tenía una forma conjugada del verbo "convocar". (La frase exacta era convoca a los estados americanos.) Aunque estoy familiarizada con la palabra, no tengo ocasión de usarla mucho, así que decidí buscarla para asegurarme de que la conocía bien. En el proceso, noté que algunos ponen una "a" después de este verbo y otros no. Para descartar que esta "a" que parecía estar en uso no fuera simplemente la "a" personal, busqué una frase que me ayudara a eliminar esa posibilidad. A través de linguatools, descubrí que "convocar (a) elecciones" es una colocación común. Entonces, fui al Google NGram Viewer para ver qué podía revelar y me mostró esto:

[Véanse arriba en la parte inglesa.]

Eché un vistazo muy superficial a algunos de los libros de estas dos frases y me di cuenta de que, en cada caso, ambas parecen ser utilizadas de manera transitoria, ambas están en voz activa, ambas son utilizadas por lo que parecen ser libros de hablantes nativos de español y ambas parecen compartir el mismo significado. Si quieres verlo por ti mismo, puedes enlazar con el Ngram aquí.

Obviamente, una se usa con más frecuencia que la otra, y una - convocar a elecciones - parece ser ligeramente más antiguo que la otra frase si la colección de Google puede ser un tipo de indicador. Según el Google Ngram Viewer, la variante con la "a" se utiliza al menos desde 1841 y la variante sin "a" no aparece hasta 1863. Aparte de eso, no veo mucha diferencia. Por eso me lleva a la pregunta: ¿Es la "a" opcional y en todos los registros? Si no es opcional, ¿hay algún matiz en el significado que me falta? ¿Cómo sabré cuándo usar cuál?

Traducción realizada, en parte, con la versión gratuita del traductor www.DeepL.com/Translator.

Answer 1

There are a couple of likely explanations for this. On the one hand, convocar has in fact two possible usage patterns. As the DPD says, it can mean both “call someone to something” or “call for something”. The expression “convocar elecciones” is an example of the latter; here the thing called for (elecciones) is the direct object.

The alternative “convocar a elecciones” should appear only when there's another object pointing to those who have been called, for example “convocar a la ciudadanía a elecciones”. Note that in this case the personal a has to appear, because the referent will always be specific and animate (in this case it's a collective).

I myself find this alternative more acceptable, even without a direct object. I suspect that “convocar a elecciones” without an overt direct object is deemed correct by a lot of people for two reasons at least: one, because it can be readily interpreted as a stock phrase where the direct object is almost always understood; two, because it's very easy to let this somewhat learned term follow the pattern of the much more common llamar, which always has a preposition a introducing its object (in this meaning): “llamar a elecciones”, “llamar a un plebiscito”, “llamar a la insurrección”, etc. The nominal expressions also need this preposition with both verbs: “llamado a la solidaridad”, “convocatoria a elecciones”. Everything, in other words, suggests the speaker that there has to be an a before the object of verbs that mean “to call, to invoke, to summon”, etc. For some people, in a way, the verb convocar has become inherently prepositional; that the preposition used in this case is the one used to mark indirect objects might be incidental.