Learn Danish: Politikerne må forholde sig til problemet. - The politicians have to deal with the problem.

While håndtere means to practically manage or fix a situation, forholde sig til is more abstract. It literally means to relate oneself to something. In Danish debates, it is the standard phrase for taking a stance, forming an opinion, or officially addressing an issue. The politicians are being asked to face the problem, not necessarily to physically fix it yet.

Could I use skal instead of må to mean "have to" in this sentence?

Yes, but it changes the nuance. Skal often implies a direct command, a firm promise, or a fixed plan. Using må here expresses an inescapable logical necessity or an urgent recommendation, suggesting that the politicians have no choice left but to address the problem.

Why is the reflexive pronoun sig required here?

The verb phrase meaning to relate to or take a stance on something is strictly reflexive in Danish: at forholde sig til. You must match the pronoun to the subject. Because the subject is politikerne (they), you use the third-person reflexive pronoun sig.

Why is the definite plural politikerne and not politikerene?

When a Danish noun ends in -er, like en politiker, adding the standard definite plural ending -ene would create an awkward extra syllable. To make it easier to pronounce, Danish drops the extra 'e' and just adds -ne, resulting in politikerne.