This is the latest installment in a series of reading guides on 2012 presidential candidates. Here are the other guides.This guide was most recently updated on November 30.

The basics:

Former Speaker of the House Newt Gingrich got off to a rocky start. He was behind most of the other presidential hopefuls in terms of fundraising, and his campaign staff also quit en masse earlier this year over concerns that Gingrich was not taking campaigning seriously.

But since then, Gingrich has been gaining in the polls—and with his new prominence has come increased scrutiny of his record.

Gingrich is perhaps best-known for his foibles, including his spectacular fall from power in the late 1990s. But he is also a bold ideologue who during his time as speaker in the late 1990s successfully pushed for reducing taxes and scaling back welfare.

Gingrich also holds some views that do not fit the conservative mold. He has partnered with Hillary Clinton to advocate health-care IT legislation, with Al Sharpton and Arne Duncan to promote President Barack Obama's education reforms, and with Nancy Pelosi in an ad stressing the importance of taking action on climate change.

Gingrich angered Republicans by criticizing Paul Ryan's plan to reform Medicare, prompting the American Conservative to accuse him of never really having been a conservative in the first place.

Background and views:

A self-described "ideas man," Gingrich is the author of 23 books. Weekly Standard Senior Editor Andrew Ferguson has a helpful summary of his oeuvre. The takeaways: Gingrich is fond of saying that the United States is at a crossroads and that technology will lead us away from catastrophe. His earlier books are filled with rapid-fire streams of ideas for bettering society, often without details about how to implement them.

"Gingrich's vagueness was always a problem," wrote Ferguson. "But the books show something more: a near-total lack of interest in the political implementation of his grand ideas—a lack of interest, finally, in politics at its most mundane and consequential level."

Gingrich has a Ph.D. in history, and told the New York Times in 2009 that he subscribed to the theory “that certain great leaders must endure a long political exile before returning to power.”

As the New York Times detailed, Gingrich has pushed to reinvent himself in part by putting a new emphasis on faith. He recently told supporters that he believes America is becoming too secular. Gingrich converted to Catholicism after marrying his third wife, Callista, in 2000. In a 2009 Weekly Standard opinion piece co-authored with Callista, Gingrich wrote that religion was key to the triumph of the capitalist West in the Cold War. In his words, "the spiritual nature of man and the freedom to know God were central to defining humanity and decisive in defeating tyranny."

Gingrich has been outspoken about his opposition to same-sex marriage. (An activist glitter-bombed him earlier this year to protest Gingrich's stance.)

He set himself apart from other Republican candidates in November by endorsing what he called a “humane” approach to illegal immigration, which would create a path to legal status for immigrants who have been in the U.S. for decades.

Record as congressman and House speaker:

Gingrich achieved the peak of his influence in the mid-1990s. In 1994, he co-authored the Contract With America, a Republican wish list of policy changes for the 104th Congress, and saw that the 10 bills it described were all put to a vote within the first 100 days of Congress.

Gingrich is also known for helping to push then-President Clinton to balance the budget for the first time since 1969. (It's worth noting, as FactCheck.org does, that this was achieved in part through increased tax revenues.)

By some accounts, as we noted in our reading guide on Congressional dysfunction, Gingrich was also responsible for making Congress more partisan and more focused on fundraising.

According to former Republican Congressman Mickey Edwards, Gingrich pushed his fellow Republicans to focus less on actually making laws and more on being “a champion of the Republican cause, constantly at war, defeating Democrats."

Time magazine named him Person of the Year in 1995, describing him as a man who "changed the center of gravity" in Washington and who has "transformed both the House of Representatives and the Speakership into unprecedented instruments of personal and political power."

As House speaker, Gingrich introduced three plans for welfare reform, the first two of which Clinton vetoed; the third became law.

The deeply controversial law helped drive a huge decline in welfare cases. A report from the Brookings Institution found that caseloads declined about 60 percent in the decade after the law was signed. But as USA Today has detailed, the results have not all been positive.

Gingrich's reign came crashing down in 1999, when he resigned as speaker after the midterm elections and was eventually reprimanded for an ethics violation, though, as we detail below, he was eventually cleared of charges related to it.

Scandals and controversy:

Gingrich was criticized for petty recalcitrance that resulted in longest federal government shutdown in U.S. history. Though the shutdown occurred because of a disagreement about how to balance the budget, Gingrich said that Republicans were playing hardball in part because Bill Clinton had snubbed him during a trip to Israel for Prime Minister Yitzhak Rabin's funeral.

The New York Post caricatured Gingrich as a baby throwing a tantrum, with the caption, "He closed down the government because Clinton made him sit at the back of the plane." In an interview with Time during the shutdown, Gingrich said, "My strength and my weakness is that I see normally impersonal events vividly and personally."

A few months later, Gingrich became the first speaker of the House to be disciplined for ethics violations. Gingrich was accused of violating tax law and providing the House with inaccurate information about how he financed his side projects. Eighty-three of the 84 ethics charges against him were later dropped, and the IRS ultimately cleared Gingrich of the final charge after he had resigned in 1999. If you want to dig into the details, the Washington Post has an archive of their probe coverage.

Gingrich is also known for having had a six-year affair with his now-wife, then-House staffer Callista Bisek, while he was married to his second wife, Marianne Ginther. Esquire has an interesting profile of Gingrich based on interviews with his second wife. Ginther describes how Gingrich told her about the affair right after giving speeches about family values, and says that he initially asked her if she could just tolerate the affair.

Gingrich admitted in 2007 that he was having the affair while he was pushing for President Clinton to be impeached over the Monica Lewinsky scandal. Gingrich and Callista have been married for 11 years, and as the New York Times detailed earlier this year, Callista plays a prominent role in his campaign.

Financial Ties to Freddie Mac:

On November 16, Bloomberg News reported that Gingrich had received between $1.6 and $1.8 million for his consulting services to mortgage giant Freddie Mac.

Republican presidential candidates—as well as New York Mayor Michael Bloomberg—have endorsed the myth that it was Fannie Mae and Freddie Mac’s mandate from the government to extend more loans to low-income Americans that caused the subprime mortgage meltdown.

Gingrich himself said earlier this year that Barney Frank should be put in jail for his ties to a Freddie Mac lobbyist, and that President Obama should give back any donations his campaign received from Fannie or Freddie executives, the New York Times reported.

Gingrich, who did not immediately confirm exactly how much Freddie Mac had paid his consulting company, The Gingrich Group, said earlier this month that he had been acting as a “historian,” and that he warned Freddie about “making loans to people who have no credit history,” saying, “This is a bubble. This is insane.”

But Freddie Mac officials interviewed by Bloomberg and by the New York Times disputed this account, saying they had never heard Gingrich make that kind of warning.

Instead, the officials said, Gingrich advised Freddie Mac on how to craft its policy message to appeal to conservatives.

Mitchell Delk, Freddie Mac’s chief lobbyist, told Bloomberg that Gingrich consulted with executives about a program to expand home ownership, and how this plan could benefit Republicans, “particularly their relationship with Hispanics.”

“Freddie wasn’t spending $25,000 to $35,000 a month for years to have somebody give them history lessons,” one anonymous former official told the New York Times.

Both Gingrich and Delk said that Gingrich provided strategic advice, but did not do any lobbying for the company.

While Freddie and Fannie may not be responsible for the mortgage meltdown, they have a spotted history, currently owe taxpayers more than $180 billion in bailout funds, and continue to lose money.

What he's been up to since 1999:

The Wall Street Journal has a good rundown through the various businesses and fundraising gigs Gingrich has been involved in since leaving Congress. In 2007, Gingrich started American Solutions for Winning the Future, which raises money to advocate for a variety of conservative causes. Though the group shut its doors this summer in preparation for Gingrich's presidential run, he has kept access to the valuable network of 1.3 million potential supporters.

Gingrich also runs the Center for Health Transformation, a for-profit group whose members are health insurers and drug companies. According to the Wall Street Journal, the companies pay big membership fees, and "in return, they get access to Mr. Gingrich, interaction with other group members, and marketing and research support."

On November 29, the New York Times reported that Gingrich did not simply provide advice to the Center’s clients—he has also promoted their services to lawmakers.

Companies pay between $20,000 and $200,000 a year to belong to the center, and Gingrich has touted the center’s members in speeches to lawmakers, brochures, and at least one hearing. Gingrich has said repeatedly that he has never taken a position for money, but, the Times reported, “he and his staff did many of the same things that registered lobbyists do.”

In 2007, Gingrich and Callista co-founded Gingrich Productions, which churns out books and films. Their latest offerings are a book on American exceptionalism, a documentary on Pope John Paul II, and a best-selling children's book on American history by Callista. They've also produced films in conjunction with Citizens United, the nonprofit group at the heart of the Supreme Court decision allowing unlimited corporate spending in political elections.

Following the money:

OpenSecrets.org has a rundown of Gingrich's top campaign contributors. According to the New York Times' interactive guide to the 2012 candidates' fundraising efforts, as of September 2011, Gingrich had raised only $2.9 million, putting him behind well most of his competitors.