By Lianna Brinded June 17, 2014 09:40 BST
The unofficial referendum is meant to be a litmus test over how Hong Kong citizens view the pace of political reforms in the country after Communist Party leaders in Beijing promised change when it reverted back to Chinese rule in 1997.
However, according to the site's organiser Benny Tai, the system was flooded with "billions of visits" meaning that the poll on political dissatisfaction cannot be reached by voters at this time.
"We are considering, if the online system does not work as planned, we may extend the voting time so that we can get as many votes as possible, as planned," said Tai.
"We had hoped to get around 200,000 votes, even 300,000. Nothing will deter us from going on. We will continue."
He added that citizens will be able to cast their votes at 15 stations across Hong Kong on 22 June if the website remains down.
A DDoS attack seeks to disrupt websites and other computer systems by flooding the targeted organisations' networks with computer traffic, and viruses. It is much harder to deflect than a regular Denial-of-Service (DoS) attack as there is simply no single attacker to defend from.
A regular DoS attack targets and is carried out by one computer and one internet connection, which overwhelms just a single server with packets of data.
Tai, associate professor of law at the University of Hong Kong, the referendum's organisers will decide on how to proceed with the results, only after the outcome of the vote.