It is virtually a foregone conclusion that either Mr David Burnside, of the UUP, or the Rev William McCrea, of the DUP, will win the South Antrim by-election. There is also considerable interest, however, in the contest between the SDLP and Sinn Fein.
The battle between the SDLP candidate, Mr Donovan McClelland, and Mr Martin Meehan, of Sinn Fein, is being viewed as another indicator of who will eventually corner the lion's share of the nationalist vote.
South Antrim is unionist territory but the nationalist population is increasing gradually.
While the SDLP is in the ascendant, former IRA prisoner Mr Meehan believes he can build a solid base for Sinn Fein.
In the 1998 Assembly election the SDLP's two candidates polled 7,783 first preferences between them, compared to Mr Meehan's return of 3,226 votes. Mr McClelland, a councillor in the Antrim borough, won an Assembly seat for the SDLP, making him the only nationalist representative in the constituency.
South Antrim takes in the councils of Antrim and Newtownabbey. The SDLP has four councillors in Antrim and one in Newtownabbey, while Sinn Fein has one councillor in Antrim.
Mr Meehan says that in the next council elections Sinn Fein will be in a position to take an additional two seats in Antrim and two in Newtownabbey.
In areas of South Antrim where there is a reasonably strong nationalist population, such as Toome, Glengormley, Randalstown and Crumlin, Mr Meehan says Sinn Fein is making inroads into the SDLP vote.
Mr McClelland took time off in the middle of this campaign for a holiday with his wife, which Mr Meehan interpreted as "showing contempt for the voters". An SDLP source explained that the holiday was a 25th wedding anniversary vacation organised long before the by-election.
"The reality is that I can't win this election," Mr Meehan conceded before going canvassing with Sinn Fein chairman Mr Mitchel McLaughlin, "but I can expand the Sinn Fein influence in South Antrim, and put the party in a position to win an Assembly seat next time around."
The challenge for Mr McClelland as he returns to the fray is to resist the Sinn Fein threat. Party representatives say the SDLP is getting a positive response on the doorsteps. If Mr Meehan improves his vote, Sinn Fein will claim this is a portent of what's to come for the party throughout the North. Should Mr McClelland maintain or improve his party vote, the SDLP will contend that it is still the main nationalist voice.
Accordingly, when the votes are being counted late on Thursday night, Mr McClelland and Mr Meehan will be checking the tallies just as avidly as Mr Burnside and Mr McCrea.
A UUP councillor, Mr Tom Robinson, warned last night of a threat to Mr David Trimble's leadership if Mr McCrea wins. Mr Robinson, an alderman on Larne Council, told the Lisburn branch of the UUP: "If David Burnside fails to win and win conclusively in the South Antrim by-election, the ability of any Ulster Unionist candidate to win under the current leadership will be questioned, as too will Mr Trimble's capacity to unite the party."