Learn Spanish (Latin America): Era importante que nadie votara contra el proyecto. - It was important that nobody vote against the project.

The triggering phrase in the first half of the sentence, era importante que (it was important that), is in the past tense. When a past tense expression triggers the subjunctive, the verb that follows must also be in the past. That's why we use the imperfect subjunctive votara.

How exactly do we build the form "votara" from the verb "votar"?

To form the imperfect subjunctive, you always start with the "they" form of the preterite (simple past) tense. For votar, that is votaron. You drop the -ron at the end to get your stem (vota-), and then add the imperfect subjunctive ending. Since the subject here is nadie (a third-person singular subject), we add -ra to get votara.

Doesn't the imperfect subjunctive form "votara" also mean "I voted"? How do we know who is voting?

Yes, it does! In the imperfect subjunctive, the yo (I) form and the él/ella/usted (he/she/you formal) forms are identical. Context is key. Here, we know the verb belongs to nadie (nobody) because the subject is explicitly stated right in front of it.

Why isn't there a "no" before the verb? I thought Spanish used double negatives with words like "nadie".