Stockman said that McCain's team is ignoring his previous commitments on this issue and is intentionally downplaying his clout.
"If McCain chooses not to revise the platform, I think he will say it's 'the system' and he will try to distance himself from it," said Stockman. "But he absolutely has the power to change it."
"Many people think of him as a moderate," she said. "But when it comes out that he doesn't want to change this extreme, right-wing Republican platform, the word 'moderate' is going to disappear from any description of McCain."
ABC News' Talal Al-Khatib contributed to this report.