Chris Christie's stunning turnaround in a key metric helps explain his abrupt reversal of fortune

New Jersey Gov. Chris Christie (R), long an afterthought in the 2016 presidential race, may be having a bit of a moment.

Christie's campaign once looked so quixotic that a super PAC determined to defeat him closed up shop last summer, saying it was no longer necessary. He languished for months at the bottom of the polls and was ignored by his 2016 foes.

But Christie has suddenly turned into a pincushion for his rivals' barbs.

Former Florida Gov. Jeb Bush (R) pointed this week to New Jersey's credit downgrades. And allies of Sen. Marco Rubio (R-Florida) and Ohio Gov. John Kasich (R) launched a multipronged ad attack against him.

Christie - who has not hesitated to trash-talk his rivals, either - attributed the attention to his increasingly solid position in New Hampshire. "We've got a message here in New Hampshire that's resonating with voters," Christie reportedly said Wednesday of his opponents attacks.

Christie's argument here has some basis: The governor has been surging for weeks in polls of New Hampshire, the influential first-in-the-nation primary state. Christie is now roughly tied with several others there for second place, behind GOP front-runner Donald Trump.

But looking deeper past the top-line numbers in the polls, Christie has managed an even more striking turnaround: his favorability numbers.

In a Public Policy Polling survey of Republican voters last August, 46% of respondents said they had an unfavorable opinion of Christie, compared to 35% who said they had a favorable opinion. That was a 11-point deficit among Republican voters.

But in another PPP New Hampshire poll published this week, 53% of likely GOP voters said they had a favorable opinion of Christie, while just 29% said the opposite. So, according to this survey, at least, Christie now has a net 24-point positive margin. It amounts to a 35-point swing since August.

But PPP was hardly the only poll to find good news for Christie's favorable numbers in recent weeks.

According to Adrian Gray, the president of AGC Research who posted several poll averages on Twitter, Christie's net favorables have also reversed themselves in the early-voting states of Iowa and South Carolina: