The tweet finally landed at 4:19 p.m. Wednesday. Former House speaker Newt Gingrich, a fixture in the Republican Party for three decades, became a candidate for president.

Though it was long expected, the announcement was something of a milestone in presidential politics — the first such declaration via Twitter, with the requisite link to his video statement.

Like others in the Republican field, Gingrich, 67, has been moving steadily toward a candidacy for months. But in formally declaring, he set himself on an uncertain journey that will test whether his assets can overcome his liabilities.

There are many questions he will confront. Gingrich is an idea-spewing machine, unlike anyone else in the Republican Party. But does America want a one-man think tank, particularly one with his history, as its president?

Is he yesterday’s man at a time when Republicans may want a fresh face? A number of GOP strategists think his time has passed, though he obviously does not and looks to history for inspiration.

Is he professionally disciplined enough to be a successful presidential candidate? His record in public life suggests otherwise. He vows this will be different.

Will his personal life — multiple marriages and an admission of adultery — prove disqualifying to social conservatives? Many think it will. His hope is that Americans like stories of confession and redemption.

Gingrich says that he has learned from his mistakes, that he begins this campaign in a different frame of mind. He claims he will listen to those around him, including some of his newest advisers. He says he will take seriously the advice he receives from others. If that turns out to be true, it will mark a distinct change in his modus operandi.

His announcement stressed his work with President Ronald Reagan in the 1980s and his accomplishments when he was speaker during the 1990s (though with no mention of the work he did in cooperation with President Bill Clinton).

“There’s a much better American future ahead, with more jobs, more prosperity, a better health system, longer lives, greater independence, a country decentralized under the 10th amendment, power once again back with the American people,” he said.

Some of those who watched him over the years remain skeptical that Gingrich can overcome his liabilities. “Everybody thinks they know who Newt is, and a significant portion don’t think they like him, and he’s going to have to convince them,” said Rich Galen, a GOP strategist and former Gingrich adviser.

Still, Gingrich brings to the race an unparalleled record in his party as someone who has remained in the forefront of the public policy debate over a span of decades. If he has lacked discipline in other areas, the one consistency in his public career is a devotion to the intersection of ideas and politics. He has made himself a force in whatever role he has played: as a backbencher, as House leader, and for more than a decade as a politician without office or official portfolio.

Through intellect and ambition, Gingrich has kept himself in the middle of public policy debates on health care, education, energy and foreign affairs. “Newt’s been the Republican Party’s main idea man for close to a generation,” said Terry Holt, a Republican strategist who closely observed Gin­grich as speaker. “This is a guy who brings unlimited energy and creative thinking to a race that needs new ideas.”

It is that part of Gin­grich that most appeals to many Republicans. Put Gingrich in a room with Republican voters and most will come away impressed. “The brightest political figure I’ve ever met,” an Iowa Republican activist told me this year.

He draws from history, from futurism, from technology, from white papers, from today’s headlines to make his case for conservatism’s superiority. “He is mesmerizing with our [Republican] people in small rooms,” said Don Fierce, a GOP strategist who was a top official at the Republican National Committee when the party took over Congress in 1994.

The knock on Gingrich, of course, is that he throws out ideas so rapidly that he can barely distinguish between good and bad ones. As the story goes, the staff at the National Republican Congressional Committee used to keep a file cabinet labeled “Newt’s Ideas.” Most of the space was reserved for “Newt’s Bad Ideas.”

Gingrich has operated with the philosophy that it’s better to have 25 things to say than one or two. “I think he will get relatively impatient giving the same speech a hundred times,” Holt said. “You’ve got to quit making up new stuff and take your best thing. That will be Newt’s true test.”

A keen intellect can also translate into the appearance of intellectual superiority. Gin­grich speaks in the language of both superlatives and the Apocalypse. Nothing is understated, including his diminishment of his opponents. That will not wear well on the campaign trail, unless Gin­grich finds a way to keep himself in check.

Mike DuHaime, a GOP strategist and top adviser to New Jersey Gov. Chris Christie, said Gin­grich’s propensity to be overly blunt or impolitic might not cost him in this race. “I actually think there is a place right now in our party for somebody who is authentic and who says things that aren’t poll-tested and popular,” he said. “It could turn into a liability, but it also could be a strength.”

Presidential campaigns are won not with 10 good ideas but with a relative few that inspire and motivate. For Gin­grich, the challenge will be to translate his many ideas into one larger and consistent vision for the country that connects with people. What would his real priorities be and how would he achieve them?

Gin­grich’s most obvious liabilities are well known and mostly personal. The question is whether his most obvious perceived strength — his intellectual prowess — will outweigh those others or become one more obstacle in his path.