The reason Republicans are dissatisfied with their choices and perceive the vacuum is that no single candidate excites both the establishment wing and the Tea Party wing of the Republican Party, aside from Christie. Tim Pawlenty was acceptable to both wings (and exciting to neither), but he took himself out of the race.
Rick Perry sensed the void in the field and decided to jump into the race, hoping to fill it. Can Perry fill the void? On the one hand, he should be able to excite the Tea Party wing, which has tended to like him. On the other hand, the Republican establishment has always been troubled by concerns about Perry's electability. They do, however, generally appreciate his economic record in Texas.
Shortly after Perry entered the race, he made headlines with a remark that the Chairman of the Federal Reserve would be treated "ugly" in Texas and that printing more money before the election would be "almost treasonous." The Republican establishment immediately became concerned that Perry could be prone to extreme language and, combined with the problem of being another Texas governor, unelectable.
While the Republican establishment has not yet made up its mind about Perry, doubts about his electability have fueled more talk that Christie is needed to save the Republican Party and defeat Barack Obama. Increasingly, buzz about a potential run by Christie has found its way into the political conversation. Christie himself, however, has made no public indication that he is more open to running than before. (Though he's avoided making any convincing denials of his intention to run.)
The Christie talk isn't just a repudiation of Perry. It also demonstrates how "soft" the support is for Mitt Romney. If the establishment were satisfied with Romney, there would be no need for Christie--and certainly no need to even consider Perry.
Speculation about Christie has prompted some political strategists to research the last possible date someone could enter the race in time to meet the filing deadlines for all primaries. That date is apparently October 14th, the deadline for the Michigan primary (though Michigan will not be one of the early primaries). Elephant Watcher believes that a candidate is very unlikely to enter the race much later than the beginning of October. Until then, dissatisfied Republicans will probably spend more than a little time wondering about Christie's intentions.