CAIRO (AP) – On the eve of an Egyptian vote on a draft constitution, Islamists with swords have been fighting with opponents of that document in the city of Alexandria. At least 19 people were reported hurt.

The violence broke out after a cleric urged worshippers to vote “yes,” and described the opponents of the constitution as “followers of infidels.” Religious authorities had told clerics not to try to manipulate the vote, but several clerics told congregations today that voting in favor of the constitution is a way to seek victory for Islam.

Also today, thousands of Islamists filled a square in northern Cairo, raising pictures of President Mohammed Morsi. He has insisted the referendum will begin tomorrow as scheduled, despite accusations that the entire process has been rushed through by his Islamist allies.

The crisis escalated when Morsi issued a decree last month giving himself — and the assembly writing the constitution — immunity from judicial oversight. The document was passed several days later by an assembly composed mostly of Islamists.

It’s prompted clashes between the newly-empowered Islamists and the country’s liberals, supported by a large sector of moderate Muslims. The violence and harsh divisions have turned tomorrow’s vote into a fight over Egypt’s post-revolutionary identity.