Newt Gingrich’s rapid rise in presidential polls has left veteran Republicans wondering, and not just because he vaulted from far back to lead Mitt Romney in several key states.

They’re trying to figure out why the former House speaker is supported by GOP voters who think he’s not particularly honest and doesn’t share their values. They’re puzzled that Iowa evangelical Christians are flocking to a man who was unfaithful to two wives, paid $300,000 in House ethics fines and converted to Roman Catholicism.

They’re surprised that Republican voters say they value Gingrich’s experience far more than that of his rivals. Gingrich’s record of earning millions of dollars in the government influence business, after 20 years in Congress, seems to upend the notion that this election cycle is driven by tea partyers’ hostility to Washington insiders.

“I can’t decipher what’s going on,” said Rep. Allen West, R-Fla., one of the tea party’s best-known first-term lawmakers.

“I’ve had a little trouble figuring it out, too,” said Rep. Steve King, R-Iowa, one of Congress’ most conservative members.

Fueling the perplexity are three independent polls of Iowa Republicans, who will hold their caucus Jan. 3. They show Gingrich leading, with Romney and Rep. Ron Paul of Texas battling for second, and four others trailing.

Republican elected officials and strategists offer an array of theories. One school holds that Gingrich articulates conservative positions so forcefully that he attracts hard-right voters willing to overlook his record of inconsistencies and foibles. While many people see Gingrich as a consummate Washington insider — making $1.6 million advising Freddie Mac — his sharply anti-Washington rhetoric and unorthodox views convince others that he’s willing to buck the system and make needed changes.

Another theory, however, suggests that many Republicans simply don’t know much about Gingrich, 68, whose greatest political triumph was 17 years ago when he rose to become House speaker.

With Gingrich, “the message resonates more than the record,” said Mark Meckler, a co-founder of Tea Party Patriots. Gingrich is skilled at synthesizing and expressing conservatives’ goals and anger, Meckler said. But he also has “a long history that’s hard to explain away.”

If that’s true, it’s possible the attacks being launched against Gingrich, mainly by Paul and groups backing Romney, will take a big toll before the Iowa caucus and the Jan. 10 New Hampshire primary. But it’s also possible, some GOP analysts say, that the attacks will endear Gingrich to conservatives more than ever.

Issues and questions raised by the three polls of Iowa Republicans include:

EXPERIENCE

Separate surveys for The Des Moines Register and New York Times-CBS News showed Gingrich with an overwhelming lead on the question of which Republican has the best experience to be president and handle world crises.

That raises serious doubts about Romney’s strategy. The former one-term Massachusetts governor says his decades as a businessman are preferable to the background of someone who “has spent the last 40 years in Washington.”

Romney’s campaign this week brought out former congressional colleagues of Gingrich who said he was divisive and erratic in his four years as House speaker.

Even his toughest critics generally praise Gingrich for leading the 1994 GOP takeover of the House. But other Gingrich critics are trying to remind voters that he has favored bank bailouts, an individual mandate to buy health insurance and a bipartisan push to combat climate change. They highlight the millions of dollars he made in the Washington influence world, including his contract with Freddie Mac, a mortgage backer he publicly criticized.

But King, the Iowa conservative, said staunch conservatives know that some level of government experience is needed to change federal policies.

“The anti-Washington part of the tea party seems to have diminished a little bit,” King said. “They’ve become more sophisticated. They have a better understanding of how Washington works.”

VALUES vs. IDEAS

A Washington Post-ABC News poll found that only 13 percent of likely Iowa caucusgoers see Gingrich as the most honest and trustworthy in the field, also a fourth-place showing. Yet Gingrich easily leads on the “who would you vote for” question.

Gingrich may have struck a nerve with voters by saying the 2012 race against President Obama will be a campaign of ideas. Curt Levey, who heads the conservative Committee for Justice, said Gingrich recently told a private gathering of activists in Washington, “Don’t support me, support my ideas.”

RELIGIOUS CONSERVATIVES

In the Times-CBS poll in Iowa, Gingrich held a 2-to-1 lead over his nearest rival, Paul, among white evangelicals. He held a 3-to-1 lead over Romney, a Mormon.

Gingrich’s acknowledged infidelities and two divorces are well documented. He was having an affair with a House staffer, now his wife, when he pushed for Clinton’s impeachment over the Monica Lewinsky scandal. Some think religious conservatives will turn against Gingrich when they learn more details of his past. Others think these voters might embrace Gingrich’s story of contrition and hoped-for redemption.

ELECTABILITY

In the Times-CBS poll, nearly half of Iowa Republicans said it’s more important to pick a nominee who can beat Obama than to have one who agrees with them on the issues. Gingrich has a 23-point lead among these voters: 43 percent to Romney’s 20 percent.

Yet most polls show Obama faring better against Gingrich than against Romney in hypothetical match-ups in key states. Voters sometimes express conflicting views, GOP insiders note. And voters might believe Gingrich is stronger, or will become stronger, than the polls suggest. Many observers note, however, that much can change as the nomination process progresses.

Meckler, the tea party activist, thinks close and literal readings of the Iowa poll results can give a misleading picture of the contest. He also noted that Rudy Giuliani led the GOP field at this point four years ago, only to collapse.

He thinks many Republicans are embracing Gingrich’s robust attacks on institutions they dislike, such as the news media and congressional wheeling and dealing.

“The way he pushes back against the press is very appealing to a lot of people,” Meckler said. “People feel like he speaks for them.”

When Gingrich used “stupid” to describe the bipartisan “supercommittee,” which failed to break the political logjam on deficit spending, he expressed “our feelings exactly,” Meckler said. “We knew it would fail. It was fake.”