The more Rudy campaigned in NH the lower his poll numbers, so maybe his retreat is a secret way to garner support:

In the 21 New Hampshire polls between early July and December 10, Mr. Giuliani slipped below 20% five times, according to polls collated by RealClearPolitics.com. In the 11 polls taken while Mr. Giuliani was advertising heavily, he attracted less than 20% support nine times.
Put another way, between the beginning of July and early November, Mr. Giuliani polled an average of 21% in New Hampshire. In the following four weeks, when he was advertising heavily, support dropped to an average of 18%.