Your table is coated with a "Catalyzed Conversion Finish", just like your cabinet doors. It is an extremely hard, 2-part finish that simply can't be duplicated at home, and may not allow the new finish to adhere properly. I'd suggest a good cleaning, rinsing, and light sanding with a 150 or 180 grit sandpaper to encourage adhesion. Just be careful not to sand off any of the stain. One of the nice things about poly's is they are compatible with virtually any other finish. I'd suggest using an exterior grade poly, since it will be more resistant to moisture, spills, and cleaning. I like Min-wax Spar Polyurethane in a satin or matte finish.