The phrase "have to" is a colloquial way of expressing compulsion or obligation. It implies that the speaker has no choice or control over the matter at hand. However, there are many synonyms for "have to" that can convey a similar sense of necessity or responsibility but are more descriptive or nuanced. Some of these include "must," "need to," "should," "ought to," "be required to," "be compelled to," "be duty-bound to," and "cannot avoid." Using these alternative phrasings can help you more precisely communicate the intensity or urgency of a situation and avoid repetitive language.