The Heritage Foundation chartered a bus in late January and sent 40 Members and a handful of staffers from the House Republican Study Committee to the Four Seasons hotel in Philadelphia for a three-day retreat.

If the nonprofit, ideological think tank employed lobbyists to influence the Members it sent on the trip, as it has in the past, House ethics rules would have barred Heritage from picking up the tab.

But because Heritage alumni opened an affiliated — but separate — lobbying shop and “membership organization” in 2010, Heritage was able to pay for the trip without running afoul of Congressional travel restrictions. It cost more than $50,000, according to records maintained by LegiStorm.

Just five years ago, Congress amended its ethics rules to prohibit private groups that retain lobbyists from arranging, organizing and financing most Congressional trips that last longer than one day. But, as Roll Call has reported, Members of Congress and their staffers continue to take trips sponsored by groups that don’t lobby themselves but maintain formal affiliations with lobbyists and advocacy organizations and do so with the blessing of the House Ethics Committee.

“It gives a patina of respectability to the travel that it probably doesn’t deserve,” Campaign Legal Center’s Meredith McGehee said.

January was an illustrative month for how organizations with strong ties to lobbying interests continue to sponsor Congressional travel, even quasi-official membership retreats.

Just days before the excursion to Philadelphia, the Congressional Institute, a nonprofit with a board consisting almost entirely of registered lobbyists, spent more than $60,000 to send more than five dozen staffers to meet their bosses in Baltimore for the annual House Republican Conference retreat, LegiStorm records show.

Though lawmakers pay their own way to the meetings, the institute pays hundreds of thousands of dollars each year to send staffers to the January retreat, as well as another it hosts in the spring for chiefs of staff.

Speaker John Boehner (R-Ohio) approved 13 staffers to make the trip to Baltimore; Majority Leader Eric Cantor (R-Va.) approved travel for 11 others, according to LegiStorm records.

Every member of the Congressional Institute’s board is a current or former registered lobbyist — for organizations that include Verizon, American Express, UPS, Altria and Boston Scientific, according to OpenSecrets.org.

President Mark Strand, who last registered as a lobbyist in 2002, said lobbyists on the board “don’t have anything to do with any aspect of planning the trip. They are not involved whatsoever, they don’t speak, they don’t have a role in the events or plan the agenda.”

Lobbyists were given the opportunity to hobnob with the lawmakers and staffers at an opening reception and dinner at the Baltimore Marriott Waterfront Hotel before holding their own separate meetings the next day, Strand said.

A similar retreat for House Democrats was financed by official and campaign funds, a spokesman confirmed.

The Heritage trip to Philadelphia also is an annual event. A Republican Study Committee spokesman said Heritage reaches out to the Congressional group to get suggestions and advice before planning and underwriting the conference each year.

Last year, Heritage spent almost $125,000 to fly about 50 Members and a few staffers — along with spouses and other family members — to Simi Valley in January 2011 so they could be near the Ronald Reagan Presidential Foundation and Library for a retreat titled “In the Steps of Reagan.”

The trip was just months after foundation employees left to open an affiliated advocacy organization called Heritage Action for America, which spent more than $150,000 lobbying Congress last year.

Michael Franc, as vice president of governmental studies at the Heritage Foundation and supervisor of Congressional outreach, submits the travel pre-authorization forms to the House Ethics Committee. Franc is also a director at Heritage Action.

Heritage Action is an “organization that maintains one class of membership and its sole member is the Heritage Foundation,” according to its most recent tax filing, though a spokesman said there are 35,000 individuals who contributed financially to the organization last year.

Franc said that despite the links between the two groups, Heritage’s advocacy arm has no role in the trips the foundation plans for lawmakers.

“The retreat was a 50,000-foot extended dissertation on our founding principles” and should be distinguished from a trip pushing particular legislation, Franc said.

Heritage Action is “very targeted in terms of policy advocacy,” he added.

Critics say underwriting an advocacy arm is no different than hiring a lobbying shop, but the technical distinction allows an entity to certify that it does not “retain or employ a federally registered lobbyist” when it asks for approval from the House Ethics Committee.

“Looking just a few years back, the so-called charity Heritage Foundation itself was [a Lobbying Disclosure Act] registrant in 2006, employing the lobbying services of Foley & Lardner. Today, the foundation employs the lobbying services of Heritage Action. These are not distinct entities,” said Public Citizen’s Craig Holman, who took an active role in helping draft the 2007 reforms.