For months, Newt Gingrich has had a front-row seat from which to observe what happens when a Republican presidential candidate emerges from the pack to be touted as the next great insurgent hope and the conservative alternative to Mitt Romney.

Now it might be his turn.

“This is actually the point where other people have faltered,” Gingrich said in an interview Wednesday.

The former House speaker is rising in the polls. But whether he will become an actual threat to Romney, or just another fleeting phenom, will depend largely on two things: Gingrich’s ability to keep in check the impulses that have been his undoing in the past, and how well he deals with the criticism and scrutiny that go with being a real contender.

“Newt has to remain uncommonly disciplined — totally focused, no hissy fits — and continue to be the adult that he has been during the election season so far,” said Ken Duberstein, a chief of staff in the Reagan White House and a friend of Gingrich’s for more than three decades.

Many of those who know Gingrich are doubtful he will be able to do that. “The worst in Newt comes out when he is doing well,” said a Republican former House colleague, who spoke on the condition of anonymity so he could be frank.

Gingrich allowed that self-control has not exactly been his strong suit in the past.

“That’s true,” said the man who once accused President Obama of having a “Kenyan, anti-colonial” worldview. “Hopefully, I’m going to be more disciplined.”

But he insisted: “I’m much more relaxed and more mature than I was 12 years ago. . . . I have had 12 years to rest and to think and to run small businesses.”

One thing he will not do, Gingrich said, is go on the attack against Romney.

“I don’t need to try to get his votes,” he explained. “My campaign is going to focus on substance. My campaign is going to focus on very large proposals, the size of the challenges the country faces.”

Some of them, he added, will be controversial.

For instance, at a time when everyone else in his party is preaching government austerity, Gingrich proposes to spend billions on brain science research. Finding cures for diseases such as Alzheimer’s and Parkinson’s, he argues, is crucial to bringing Medicare spending under control as the population ages.

Gingrich’s candidacy was all but left for dead in June, after he stumbled out of the starting gate and saw most of his top advisers flee. But where another candidate might have skulked out of the race in humiliation, Gingrich retooled his operation and forged ahead, campaigning on a shoestring.

His performances in the debates have many Republicans reconsidering the Gingrich they thought they knew. On that stage, the attack dog of the 1980s and 1990s has evolved into an elder statesman, winning praise for his policy expertise and range.

But with the renewed attention have come reminders of the political baggage that he has accumulated over the decades. For instance, fliers recently appeared in Iowa reminding religious voters about his three marriages.

And his opponents are certain to draw attention to Gingrich’s ideological apostasies: the fact that he once talked favorably of requiring people to buy health insurance, a linchpin of President Obama’s health-care law; that he once said he could “strongly support” a cap-and-trade program to control carbon emissions; and that as recently as May, he referred to the House Republicans’ Medicare plan as “right-wing social engineering.”

“I think that we will have a fair amount thrown at us for a while,” Gingrich said. “It tells me that I’ve gotten back to being a serious contender.”

On Wednesday, for instance, Gingrich’s campaign had to explain a Bloomberg News report that he had received between $1.6 million and $1.8 million in consulting fees for advising Freddie Mac, a federally backed housing giant that is despised by conservatives and that collapsed in the financial crisis.

Gingrich told reporters in Iowa on Wednesday that he doesn’t know how much money he was paid by Freddie Mac. His campaign sent out a statement saying that Freddie Mac was a small part of the Gingrich Group’s client base, and that the candidate had never lobbied on behalf of Freddie Mac or any other client.

The scrutiny he is getting comes with the territory, Gingrich acknowledged.

“I’ve been through long periods of tough media,” he said. “This is the presidency. There are no unreasonable questions.”

As he enjoys a political resurrection that few would have thought possible just weeks ago, Gingrich said he is well aware of how transient such a moment can be.

Consider what has happened just since August.

First there was Rep. Michele Bachmann (Minn.), who enjoyed a brief surge that peaked when she won a GOP straw poll in Ames, Iowa. That momentum was squashed by Rick Perry’s entry into the race — until the Texas governor turned out to be a dud on the debate stage. And then came the fleeting star turn of onetime Godfather’s Pizza chief executive Herman Cain, whose candidacy has faded somewhat amid sexual harassment allegations and his increasingly apparent lack of depth on the issues.

Meanwhile, Romney has remained the presumed man to beat, although his failure to open a healthy lead in the polls suggests that the former Massachusetts governor is still a long way from winning the hearts of his fellow Republicans. That means a large part of the GOP electorate is still up for grabs.

Gingrich has said that his wife and his family have been coaching him to remain calm and upbeat, and to avoid doing anything that might rekindle memories of the man who in 1995 suggested that he had shut down the government because President Bill Clinton had made him sit in the back of Air Force One.

Seventeen years later, Gingrich has learned that there are a lot worse things in politics than coming under fire.

Like not getting any attention at all.

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