Current electronic voting systems require an anonymous channel during the voting phase to prevent coercion. Typically, low-latency anonymization-networks like Tor are used for this purpose. In this paper we devise a monitoring attack that allows an attacker to monitor whether participants of an election voted, despite the use of a low-latency network during the voting phase, thereby breaking an important part of coercion-freeness. We implement a simulation carrying out our attack and measure its success rates.