After running an unconventional, surprisingly strong and sometimes strange race to the top tier of the Republican presidential campaign, the former Arkansas governor topped himself on Monday with an eyebrow-raising campaign stunt.

He called a news conference to unveil a negative ad that he had just withdrawn from Iowa television stations because, he told a room full of journalists recording the ad, he had a sudden aversion to negative politics. Quite a convenient epiphany.

“If people want to be cynical about it,” Huckabee said, “they can be cynical about it.”

If he loses Iowa’s caucuses on Thursday, New Year’s Eve will forever mark the day Huckabee blew it — the day a group of reporters stopped laughing with the witty Republican and laughed at him.

If he wins — a possibility that even Huckabee now thinks he put at risk — he sealed victory in a weird way Monday.

Here’s what happened: Huckabee came out of nowhere a few weeks ago to overtake former Massachusetts Governor Mitt Romney in Iowa polls, despite being massively outspent and out-organised. Romney answered back with television ads criticising Huckabee’s record in Arkansas. Huckabee’s lead evaporated, which suggests the ads worked or that a series of gaffes had caught up to him.

So he did what desperate candidates do. Huckabee took himself off the campaign trail on Sunday to shoot a negative ad. He bought $30,000 in television time to air the spot and called a news conference to unveil it.

While awaiting the late-arriving Huckabee, more than 50 reporters and a dozen photographers got to read five huge cards placed on easels by Huckabee’s staff — all highly critical of Romney’s record as governor. “Enough is enough,” the signs said.

When Huckabee arrived, he announced he had just changed his mind. The ad would not run. It was too negative. “I believe the people of Iowa deserve better, and we are going to try and give them better ...,” he said. But he did not. Instead, Huckabee showed off the spot to the journalists, knowing full well his negative message would seep out of the room. He told the media to pay close attention.

One of the funniest, most charming presidential candidates in recent memory, Huckabee normally makes reporters and voters laugh at his one-liners. On Monday, he made himself the butt of his own joke, urging journalists to take careful note of the negative ad he had withdrawn because he wanted to run a positive campaign.

“It’s never too late to do the right thing,” he said.

The ad criticises Romney’s record as governor, fairly so, but goes on to question his character. “If a man is dishonest to obtain a job,” Huckabee says in the ad, “he’ll be dishonest on the job.” Funny that Huckabee decided at noon that that line was too negative, because he used it six hours earlier during a national TV interview.