Good campaigns learn from their failures.
In 2000 John McCain was undone by several factors. Everyone remembers the negative tactics against him in South Carolina--less remarked upon was George Bush's succesful effort after the New Hampshire primary to cast himself as a "reformer with results." You can bet that John McCain remembers--by allowing then Gov. Bush to appropriate the reform mantle from him, McCain lost a huge advantage he had in that race.
Now McCain is attempting to cast himself as a change agent, in much the same way that Bush in 2000 cast himself as a reformer. The McCain campaign knows that voters are looking for change, and by saying the word enough times they hope to reduce the enormous advantage that Senator Obama has enjoyed on the critical issue of "who would best bring about change the country needs?"
(We underwent a similiar effort on the Clinton campaign, driven by the same imperatives, around labor day in 07 by arguing that strength and experience was necessary to bring about change.)
McCain's claim is dubious, but up to now the effort has been somewhat successful--a recent Newsweek poll shows that McCain has narrowed a 24 point gap on this question to just five points since June.
Luckily for Democrats McCain can't always keep the storyline straight--yesterday, at the same time that he was calling for (unspecified) changes in Wall Street regulations, he was also calling the "fundamentals" of the economy "strong." And at the same time that McCain is doing everything he can to associate himself with change, the Obama campaign is fighting back just as hard to remind voters of Sen. McCain's long tenure in office and close association with President Bush.
Look to see the campaigns battle over this issue up through November. The McCain campaign knows it can't win if he is behind on the change question by 24 points--and the Obama campaign knows if that gap is in single digits their job will be may much harder on election day.