Here is the law:
(2) Each political party or political body represented on the official ballot may have one technically qualified person, authorized by the county chairman and deputized by the county board of elections, present during the testing of the central automatic tabulating equipment and the actual counting of the ballot or district totals cards. Such persons shall be allowed to make independent tests of the equipment prior to, during, and following the vote count: Provided, however, That such testing shall in no way interfere with the official tabulation of the ballots and district totals cards. In addition, each political party or political body shall be entitled to have observers at the central tabulation center, in a number, as determined by the county board of elections, sufficient to permit accurate observation of the receipt, handling, duplication, and processing of all ballots and district totals cards.
Watchers allowed in the polling place under the provisions of this act, shall be permitted to keep a list of voters and shall be entitled to challenge any person making application to vote and to require proof of his qualifications, as provided by this act.