Tafelsig voters go to the polls on Wednesday in a crucial by-election that will test the sustainability of the DA-led multiparty government in the city and shape the future of the ID.
A hard-fought campaign comes to a close on Tuesday with both the DA and ID hoping for a good turn-out after intensive door-to-door canvassing.
DA strategists say this is the party's most important by-election in a decade, since it presents a key opportunity to undermine the ID's chances of gaining credence as an alternative opposition to the ANC.
And the ANC's deputy secretary in the Western Cape, Max Ozinsky, said that while the party was not contesting Ward 82, "the by-election is very important because if the DA won, it would get another seat in council and it makes sense that we see the ID retain that seat". The party counted on its supporters voting for the ID, he said.
Either way, the result will have far-reaching implications that will be felt well beyond the economically depressed suburb of Tafelsig.
The result will be awaited with some anxiety by the only major party that is not contesting Ward 82: the ANC's chances of regaining a foothold in Cape Town before another election could depend on an ID win.
The vote is the first test of the ID's strategy of siding with the ANC against the DA-led coalition in key votes.
A DA win could lead to a haemorrhaging of ID support, with some DA strategists not ruling out further resignations from the ID, and possibly more by-elections.
Ranged behind the DA's Sheval Arendse - who won the ward for the ID in March, but resigned over the party's cosying up to the ANC - and the ID's June Frans are party leaders Tony Leon and Patricia de Lille, DA mayor Helen Zille, ID caucus leader Simon Grindrod, and the considerable resources of the parties.
At stake is the DA-led multiparty forum's hope of widening the margin between its 105 seats and the 103-seat bloc of the ID and ANC. (The PAC, with one seat, is non-aligned.)
The ANC has tacitly endorsed the ID campaign.
In the March 1 poll, the ID and DA were quite evenly matched: the ID took the ward with 2 312 votes (39 percent), with the DA polling 2 166 votes (36,54 percent), just 146 fewer. The ANC came in next with 867 votes (14,63 percent), followed by the ACDP with 229 (3,86 percent). The voter turnout was less than 50 percent.
The ID has been tackling the DA on what it claims are "swartgevaar tactics". De Lille is reported as having said at the weekend: "What the DA is trying to do is use swartgevaar tactics indirectly by telling people we are with the ANC."
Meanwhile DA leader Tony Leon has laid a charge of crimen injuria over a fake pamphlet distributed in Tafelsig, purportedly from the Africa Muslim Party and defaming him and his wife. The DA said this was "a racist, hate-mongering defamation of Tony Leon and his wife, Michal", accusing them of being Zionists who supported "racist and murderous" Israeli government policies. The AMP has issued a statement saying the pamphlet was a fraud.