Boss gave verbal agreement in meeting (witnesses) for bonus but wont pay. Do I have any recourse?

My employer promised bonus payments for certain completed tasks (I don't want to get into too much detail here for fear of reprisal). This promise was made only verbally, although it was in a formal meeting with many coworkers as witnesses. This year, I had 6 instances that met the stipulations of this bonus plan. I received payment for two (as did other coworkers), but am still awaiting payment on the remainder. I fear my employer will back out on this deal. Additionally, my office is undergoing a forced relocation out of state. I feel like this issue could be used as leverage against me in making that decision. Do I have any recourse? More importantly, is this worth fighting for? Total amount owed is ~$5k. Thanks.