Outside groups spent more than $3.6 million last year to send members of Congress and staffers on trips to far-flung locations such as Indonesia, Israel, Ghana and Turkey, a figure that could increase as late filers submit their post-travel disclosure forms.

Though the sum spent in 2012 was less than the nearly $6 million laid out the year before, it still marked a high point for election-year travel since Congress tightened its restrictions on trips sponsored by outside groups in 2007.

Year-end tallies by the website LegiStorm show that privately sponsored travel drops during election years, when lawmakers spend more time on the campaign trail, and surges during odd-numbered years.

Ken Boehm of the National Legal and Policy Center, a nonprofit that promotes ethics, says there are “overt” and “covert” reasons that organizations sponsor congressional travel.

The trips can be valuable opportunities for lawmakers and their staffs to get out into the field at no added cost to taxpayers. But they can also give special interests a chance to influence legislation and policy, a prospect that led Congress to amend travel rules in 2007 as part of a larger effort to curb the influence of lobbyists.

The restrictions capped most trips funded by entities that employ lobbyists at one day, though exceptions were written into the reforms for nonprofit groups, colleges and universities. Organizations that do not lobby but are closely linked to those that do are not barred from sponsoring travel.

“Congressmen are frequently accused of living inside a bubble. So you can make a good case that members should be traveling and getting to see certain things overseas,” Boehm said.

“But all too often they have been arranged by groups that have very pronounced legislative interests,” he added. “And what’s more enticing than having the possibility of talking [to lawmakers] in a relaxed, vacation resort-type setting?”

The American Israel Education Foundation spent more than $650,000 last year — more than any other group — to send more than 60 lawmakers and staffers to Israel for tours of Jerusalem, seminars on Israeli politics and discussions of asymmetric warfare, according to congressional travel filings.

The foundation’s main purpose is to fund these “educational seminars to Israel for members of Congress and other political influentials,” according to its mission statement, which was emailed to CQ Roll Call by a representative from the American Israel Public Affairs Committee, its affiliated lobbying organization.

The nonprofit Aspen Institute spent nearly $500,000 on trips last year, according to records kept by LegiStorm. It paid for bipartisan groups of congressional staffers to attend conferences in Maryland and Tennessee. Its Congressional Program, a division devoted to nonpartisan educational programming for members of Congress, sent lawmakers to an energy policy conference in Sao Paulo and to San Diego to discuss China.

Aspen Institute Congressional Program Executive Director Dan Glickman, a former Democratic representative from Kansas, said bipartisan groups of lawmakers are sent to conferences three or four times a year for much-needed relationship building.

“In this day and age they are actually more important than they’ve ever been before,” Glickman said. “It’s really one of the only times that members of Congress spend time with one another in a bipartisan way.”

Glickman said no registered lobbyists attend any of the group’s events.

The Congressional Institute, a nonprofit “dedicated to helping members of Congress better serve their constituents,” spent nearly $200,000 in 2012 to send dozens of staffers on two annual retreats that it sponsors each year.

Last January, the institute paid for more than five dozen staffers to meet their bosses in Baltimore for the annual “Congress of Tomorrow” retreat for the House Republican Conference. In May, it paid for more than 100 Republican staffers to attend a chiefs of staff retreat in Cambridge, Md.

At the time of last year’s Baltimore trip, every member of the nonprofit’s board was a current or former registered lobbyist for corporations including Verizon Communications Inc., American Express Co. and UPS Inc., according to OpenSecrets.org.

Congressional Institute President Mark Strand told CQ Roll Call at the time that lobbyists on the institute’s board did not plan the trip, shape its agenda or address the group. But they were given the opportunity to network with lawmakers and staffers during a reception before holding separate meetings the next day.

The House Ethics Committee announced in December that it had adopted new regulations for accepting privately financed congressional travel, including heightened disclosure requirements designed to better show links between trip sponsors and lobbying interests.

“The committee will continue to examine the growth of groups related to organizations that retain lobbyists, and will continue to consider whether there is a need and fair manner to regulate further,” then-Ethics Chairman Jo Bonner, R-Ala., and ranking member Linda T. Sánchez, D-Calif., said in a statement.