Leap in to breach is an idiomatic expression referring to a situation where one takes decisive action in order to fix a problem. If you're looking for synonyms for this phrase, there are several options. You could use phrases such as "jump into action," "take the initiative," "tackle head-on," or "dive right in." Additionally, you could use more specific phrases such as "bridge the gap," "fill the void," or "cover the exposure." All of these expressions convey a sense of urgency and willingness to take action, making them useful synonyms for leap in to breach.