Councillor Teresa O’Neill has suggested Belvedere as a possible extra stop for the line, which is set to link east with west London at a cost of £15 billion.
The track is currently set to terminate at Abbey Wood, at a £130 million station which is currently being built right on the border with Greenwich.
There have been calls to extend the line to Ebbsfleet given the building of a garden city in the Ebbsfleet Valley is now under way and plans for a major theme park in nearby Swanscombe are in the pipeline.
But Coun O’Neill first wants to see the line branching out into Bexley after it opens in 2017.
She told a full meeting of Bexley Council on April 30: “It won’t be good if it flies through to Ebbsfleet and doesn’t stop in Bexley so that is where we will focus our lobbying.
“If it’s going to stop in Bexley it could stop in Belvedere.”