Newt Gingrich may face some obstacles in his bid for the GOP presidential nomination — such as defending his imperfect marital history — but it appears he will have no trouble rounding up support on K Street.

The former Speaker, who has been out of elective office for a decade, has a huge network of former staffers and House colleagues who have already pledged their support as he launches his bid for the White House.

“I really do believe that he exhibits the characteristics of leadership that are absolutely necessary to the country going forward,” said former Rep. Bob Walker (R-Pa.), now executive chairman at the lobby shop Wexler & Walker Public Policy Associates. Walker, who considers his former House colleague a longtime friend, has signed to advise Gingrich’s campaign.

Lobbyists typically back a contender out of such personal loyalty or because a candidate backs a signature client cause.

Former Rep. Bob Livingston (R-La.), who nearly replaced Gingrich as Speaker in the 1990s, is a vocal supporter.

“Win, lose or draw, he will raise the level of debate so that the issues are fully discussed and debated and intelligently heard by the voters,” said Livingston, who runs the Livingston Group. “I think he’ll be a good candidate, and he may win.”

Gingrich’s former chief of staff, Arne Christenson, a senior vice president at American Express, and another one-time aide, Jack Howard, who is also a lobbyist at Walker’s firm, are getting behind their old boss’s effort. So are other one-time staffers, including Rob Hood, a vice president at CH2M Hill, and Rachel Robinson, vice president of government relations for the American International Automobile Dealers Association.

Some of Gingrich’s downtown supporters say privately that they worry about the personal toll the presidential bid will have on the former Speaker. But no matter those concerns, they say, Gingrich can count on their help when it comes to raising money and courting inside-the-Beltway support for the effort.

Hood, who previously ran the informal Gingrich staff alumni group, called his one-time boss “the ultimate ideas man.”

“Everybody knows it, and I think that’s what we need — some new, out-of-the-box ideas to get this country back on track,” Hood said. “I have no doubt in my mind he’s got those ideas and energy to bring them to bear.”

Robinson, who was director of Speaker Operations during Gingrich’s tenure, said he truly listens to voters on the campaign trail. “He learns from them,” she added.

Gingrich, of course, isn’t the only presidential hopeful with a downtown fan base.

But one of K Street’s favorite picks for the nomination dropped out before the race really began. After making several swings through Iowa and New Hampshire and raising cash for a possible bid, Mississippi Gov. Haley Barbour opted not to enter the competition.

Barbour, a former lobbyist, boasted the support of such K Streeters as Kirk Blalock of Fierce Isakowitz & Blalock, Brownstein Hyatt Farber Schreck’s Juanita Duggan, Blank Rome partner David Norcross and his son, Reeves Barbour, who this year joined his father’s old firm, BGR Government Affairs.

Barbour’s supporters say privately that they have been in touch in recent days with the Mississippi governor and are waiting for him to endorse a candidate before they jump back into the mix. Many of Barbour’s supporters and the money they could raise will likely follow Barbour’s own endorsement, sources said.

Republican candidates such as former Minnesota Gov. Tim Pawlenty and former Massachusetts Gov. Mitt Romney also have a roster of K Street supporters. Former Rep. Vin Weber (R-Minn.) and Clark Lytle & Geduldig’s Sam Geduldig are in the Pawlenty camp. Romney’s downtown team includes Drew Maloney of Ogilvy Government Relations, Dutko Worldwide’s Ron Kaufman, Kevin Madden of JDA Frontline, who was the 2008 Romney campaign’s press secretary, and the OB-C Group’s Bob Marsh.

Even some lower-profile presidential candidates have K Street backers. For instance, Steve Fox, director of government relations for the Marijuana Policy Project and director of public affairs for the National Cannabis Industry Association, is backing Gary Johnson, the former New Mexico governor who advocates legalizing and regulating marijuana.

“He is someone that I’ve worked with a lot in the past and certainly am appreciative of his position on cannabis-related issues,” Fox said.