Very- is the answer.
Even if political pundits say otherwise. Hacking isn't just when someone steals a password. Election hacking in 2017 will, in probability be all about social engineering.
It will be similar to what we saw during the US general elections when the head of Hillary Clinton's campaign, John Podesta's personal email was subject to a phishing attack. 50,000 emails ended up in the hands of suspected foreign state agents only because he clicked on a link that led to a spurious website. Some believe that it was this massive breach that led to Clinton's failure and the FBI are now investigating the role of Russia behind it.
However, it will be unwise to think it will just be phishing attacks though! The UK's 'Register to vote' website experienced a suspected DDoS attack before the deadline to register closed weeks before the Brexit referendum. While the official report couldn't categorically state that it was definitely an attack, it could simply not be ruled out.
Social media will play a key role in this year's general elections too. Rumours about candidates on social media can gain traction very quickly and unless social media giants like Twitter, Facebook and Google do something concrete to stamp them out, they can very easily libel and slander. Twitter and Facebook are leading a charge against the propagation of incorrect news but by the time they take action, the news has usually spread to hundreds and thousands via likes and sharing.
One of the key issues here is that social media channels until now have not been seen as pivotal in shaping public opinion. While it is obvious that there can be an echo chamber effect- meaning that our 1st degree contact will have similar likes and views as us- which is why they are within our circles, it has been used with great effect during elections in the US and France.
The reigns to profiles of political parties and large organisations are usually in the hands of junior members of the publicity/marketing department- millennials who 'get' the likes of Snapchat, Twitter and Facebook. It would help election actors to not just make absolutely sure that they communicate with volunteers and grassroots workers of the dangers that lurk on the world wide web but to also make sure that they themselves keep a keen eye out for any malicious campaigns they spot on social media and report them.
Fake news, alt facts and social engineering can only be stopped if it is a collaborative effort. And when all actors understand that it presents a clear and present danger to our future.