Their choice will, of course, be working for them but will also take decisions that will reverberate across Croydon and the south.
As well as a say on matters affecting the whole borough, he or she could shift the political balance.
Labour supporter David White, of Park Hill, in East Croydon, remembers the "seismic effect" of Malcolm Wicks' election in 1992 to the former Croydon North-West constituency.
It marked only the third Labour term Croydon had seen, and foreshadowed the first Labour council run of 1994 to 2006.
Mr White, a former Labour councillor and Greater London Council member, said: "Malcolm's election meant that voters all over the borough knew there were at least two competing sets of policies (for council and government) that might be implemented."
There is plenty at stake between the competing sets of policies on borough-wide issues that might be on the table after this election.
Take the borough's libraries, which are about to be privatised under the Tory council in the face of government cuts.
Labour candidate Steve Reed, the favourite to win, pointed to his record supporting libraries as leader of Lambeth Council, saying: "This is all still possible if councils support communities and bring in new partners and investment."
That does not put him a million miles way from Tory candidate Andy Stranack, who approves of "the private sector" as a potential partner.
Mr Stranack said: "I do think that there is a role for voluntary and private sector organisations to work with the council to provide a number of public services at an efficient and effective cost."
But they are both worlds apart from Respect Party's Lee Jasper – the bookies' second favourite to win – and the Green Party's Shasha Khan.
Both candidates want to end altogether what Mr Jasper refers to as "the austerity programme", rather than trying to cope with it.
Mr Jasper said: "Poor and working people are bearing the brunt of the cuts. Libraries are a vital part of our society and we need to maintain each and every one."
Mr Khan said: "No large economy has ever cut its way out of recession."
Planning is another issue where the MP's voice in the north can reverberate southwards.
Mr Reed said he was opposed to the Government's recent National Planning Policy Framework (NPPF), which has created the controversial "presumption in favour of sustainable development".
He said: "[The NPPF] will harm the house-building we desperately need and put our green spaces at risk of unnecessary development."
Mr Khan echoed that criticism, calling it "really just a presumption in favour of development, a green light for developers".
Tory Mr Stranack, meanwhile, did not specifically address the NPPF but said he did not want building on green spaces.
He said: "We need to work hard to regenerate existing sites. That is why I am so excited about the £1 billion investment that Westfield/Hammerson are proposing for the town centre that will have positive repercussions for the whole borough."
Respect's Mr Jasper called for a "massive house-building programme", but added: "There is no reason for any further incursion into green spaces. We should be building on brownfield sites, releasing council-owned and government lands."
Questions were also e-mailed to Liberal Democrat Marisha Ray but she had not responded by deadline.
Whoever is elected, Croydon has a lot to gain if he or she can work with fellow MPs to raise the borough's collective political voice.
Speaking this week, Croydon South MP Richard Ottaway was preparing to welcome the chosen candidate.
The Conservative MP since 1992 said: "We work closely with the MP in the north of the borough and people working together can achieve results.
"We will know who it is as early as Friday morning and they will get a letter of congratulations and then we can get to work."
His welcome is unlikely to be reciprocated, however, if Lee Jasper is today's winner.
Asked this week whether he would work with his Tory colleagues in the south, Mr Jasper replied by e-mail: "Highly unlikely. Our positions are so far apart I can't see any common ground. But never say never."