Not true, at least officially. Republicans had their own contests to worry about in Iowa. Rush's announcement of Operation Chaos didn't happen until just before primaries in states like Pennsylvania and Texas after McCain had blitzed through South Carolina and Florida to appear to sew up the GOP nomination.
IIRC, Hillary won Iowa and a few early states but not by the dominant margins she was expected to and Obama's campaign didn't really take off until later when Ted Kennedy endorsed Obama, putting the whole weight of the Kennedy wing of the party up against the Clinton wing of the party.
As I recall, that is what happened. Rush’s “Chaos” was long after the initial primaries and after the Kennedy’s put their stamp on Obama.