The 28-year-old Briton looked set to be a major contender for a second series title in three years following early-season wins at Homestead and Kansas.
But the last nine races have seen him finish in the top five only twice and his part in Dario Franchitti's horror-crash saw his bad luck continue as he slipped to 119 points behind his countryman in the championship with only four races left.
"There are probably more lows now than at any other point in my career," said Ganassi driver Wheldon. "But we're working through it and we have to bounce back.
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Despite being a very long shot for a repeat of his 2005 title win, Wheldon still thinks that, if everything goes his way, he could claw his way back into contention.
"I still think I could drag myself back into contention. I am, after all, confident in my own abilities so, given the car, I can perform. I'm not gonna give an inch, or even a millimetre, for the rest of the year. That's for sure."
Wheldon's Kiwi team-mate Scott Dixon is Franchitti's closest challenger for the title - 24 points behind - and he has confirmed he will do whatever he can to help the 2003 champion overhaul the Andretti-Green racer for the remainder of the year.
"Ill help Dixy try and close the gap in, but I need to be up there at the front to do that," he added. "So there's even more reason for me to dig deep in order to run up-front."
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