SCOOP

Sara, that exchange of letters between Obama and McCain that you linked us to a while back may be reemerging as an issue:

The Clinton campaign is expected to change its tack following the emergence of John McCain as the likely Republican adversary.

The Clinton camp is expected to argue that she is better placed to deal with McCain on security and economics. Her team is also expected to bring up a testy exchange of letters between McCain and Obama in 2006.

McCain accused Obama of backtracking on a promise to support him over a bill to restrict lobbying. He accused Obama of "self-interested partisan posturing". Obama responded to say he was "puzzled" by McCain's outburst.

"It was sad to watch," said a Clinton campaign source. "He has no idea how to deal with McCain."