Learn Icelandic: Tveir flokkar hafa valdið. - Two parties have the power.

In our sentence, flokkar (parties) is the subject, so it is in the nominative case. But if you wanted to talk about "the power of the parties", you would use the genitive plural definite: vald flokkanna. The ending -anna means "of the" for plural nouns.

Why is the word for "two" written as tveir here?

In Icelandic, the numbers 1, 2, 3, and 4 change to match the gender and case of the noun they count. Flokkur (party) is a masculine noun, and since it is the subject (nominative case), we must use the masculine nominative form tveir. If we were counting neuter nouns, we would use tvö, and for feminine, tvær.

Why does vald (power) become valdið in this sentence?

The verb hafa (to have) forces its object into the accusative case. Vald is a neuter noun, and for neuter nouns, the accusative form looks exactly the same as the basic nominative form. We then add the neuter definite article -ið to mean "the power", creating valdið.

What is the singular form of flokkar, and how is the plural formed?