According to McCain, Palin has no "intention of actually running for president," but is feeling "threatened" by a loss of the media spotlight and reduced interest in the "Palin brand."

"Granted, trying to predict Sarah Palin’s next move is like trying to nail Jell-O to the wall," McCain wrote. 

Watching Palin as she "teases and distracts" attention away from the announced candidates, McCain said Palin seems as if "she’s become the ultimate party crasher for the Republican Party."

McCain blasted Palin for touring the country on a bus and stealing the spotlight at the Iowa State Fair last weekend, where Palin told The Hill that she just happened to be in the area at the right time due to her One America bus tour. "We've been invited the last couple of years, and finally this year we had the opportunity, while on our bus tour, to swing in," she said.

"The only bus tours to political events I ever went on with my father were when he was running for president," McCain wrote. "Why else would you be touring the nation in a bus?"

McCain indicated that ultimately, Palin's "antics" are dragging down the GOP chances of regaining the White House in 2012.

"The last thing our country needs right now is a president who can’t make up her mind or make tough decisions," she said.