WASHINGTON — Newt Gingrich arrived in Washington in January 1979 as a brash congressman dreaming of a Republican revival. Not quite four years later, frustrated at the pace of change, he quietly sought counsel from a man he had once worked to defeat: Richard M. Nixon.

Mr. Gingrich entered national politics in his party’s liberal wing; as a young graduate student in 1968, he campaigned for Nixon’s opponent, Nelson A. Rockefeller. Now, over a dinner in New York, the disgraced former president instructed the impatient lawmaker to build a coalition — the noisier the better.

“He said, ‘You cannot change the country unless you are interesting and attract attention,’ ” Mr. Gingrich recalled in a speech years later. “And to do that, you have to have a group.”

Mr. Gingrich promptly founded the Conservative Opportunity Society, a band of activist lawmakers who helped usher in the 1994 Republican revolution that made him his party’s first House speaker in 40 years.

But many of the conservatives who rode to power with Mr. Gingrich ultimately deserted him, while he denounced them as “petty dictators” and “the perfectionist caucus” in the waning days of his tumultuous four-year speakership.

Today as he seeks the Republican nomination for president, Mr. Gingrich, 68, remains a paradoxical figure for conservatives to embrace — a man who can “bring us together, and alienate the hell out of us,” said Senator Lindsey Graham, Republican of South Carolina, who as a House member tried to oust Mr. Gingrich in an unsuccessful 1997 coup. Many credit him with advancing their cause, yet many are deeply suspicious of him.

A look at Mr. Gingrich’s earliest days in politics, and the evolution of his thinking, helps explain the rocky relationship between Mr. Gingrich and the movement he once led. He emerges as more of a pragmatist than a purist, a believer in “activist government” whose raw ambition made colleagues uneasy, provoking questions about whether he was motivated by conservative ideals, personal advancement — or both.

On the campaign trail, Mr. Gingrich calls himself the “conservative alternative to Mitt Romney.” As he seeks to appeal to Tea Party voters, he often invokes a conservative icon, Ronald Reagan. But some say he more closely resembles another Republican president.

“Gingrich is more Nixonian than he is Reaganite,” said Vin Weber, a former Republican congressman and the first chairman of the Conservative Opportunity Society, who is on good terms with Mr. Gingrich but supports Mr. Romney. “Not in the Watergate sense, in the strategic sense. He is not an ideologue.”...