Jon Klawans contends (as do I in Jesus and His Death) that the last supper was a meal during Passover week but not the Passover meal itself, and for me the decisive element is the absence of lamb.
What then of Jeremias’s long list of parallels? It turns out that under greater scrutiny the parallels are too general to be decisive. That Jesus ate a meal in Jerusalem, at night, with his disciples is not so surprising. It is also no great coincidence that during this meal the disciples reclined, ate both bread and wine, and sang a hymn. While such behavior may have been characteristic of the Passover meal, it is equally characteristic of practically any Jewish meal.
A number of scholars now believe that the ritual context for the Last Supper was not a Seder but a standard Jewish meal. That Christians celebrated the Eucharist on a daily or weekly basis (see Acts 2:46–47) underscores the fact that it was not viewed exclusively in a Passover context (otherwise, it would have been performed, like the Passover meal, on an annual basis).
An ancient Christian church manual called the Didache also suggests that the Last Supper may have been an ordinary Jewish meal. In Chapters 9 and 10 of the Didache, the eucharistic prayers are remarkably close to the Jewish Grace After Meals (Birkat ha-Mazon).7 While these prayers are recited after the Passover meal, they would in fact be recited at any meal at which bread was eaten, holiday or not. Thus, this too underscores the likelihood that the Last Supper was an everyday Jewish meal.
Moreover, while the narrative in the synoptics situates the Last Supper during Passover, the fact remains that the only foods we are told the disciples ate are bread and wine—the basic elements of any formal Jewish meal. If this was a Passover meal, where is the Passover lamb? Where are the bitter herbs? Where are the four cups of wine?