Senate Energy and Natural Resources Committee Chairman Pete V. Domenici (R-N.M.) accepted flights and a luxury hotel stay last year from electricity interests.

Senate Foreign Relations Committee Chairman Richard G. Lugar (R-Ind.) traveled to Honolulu, Barcelona and Cancun, Mexico, where he stayed at the Ritz-Carlton -- all at the expense of the Aspen Institute.

And the Aspen Institute paid for a 15-day trip by Senate Minority Whip Richard J. Durbin (D-Ill.) and his wife, Loretta, to a conference on U.S.-Russian relations in Venice.

Those were among a wide range of senatorial travel funded by private concerns that turned up on Senate financial disclosure statements released yesterday.

Aides to the senators said the trips were worthwhile and necessary for the lawmakers to stay abreast of issues. Such trips have begun to attract attention from watchdog groups and news organizations after reports of expensive overseas travel with lobbyists by House Majority Leader Tom DeLay (R-Tex.). Most of the trip sponsors were public policy organizations such as the Aspen Institute, but some are private companies that could benefit from the lawmakers who enjoyed their largesse.

In Domenici's case, three energy interests teamed up to fund a speaking engagement Jan. 7 to 8, 2004, in Scottsdale, Ariz.

Public Service Company of New Mexico, a gas and electric utility, paid for Domenici's flight from Albuquerque to Scottsdale. Edison Electric Institute, the trade association for publicly owned electric companies, paid for his lodging. Exelon Corp., which is based in Chicago and is one of the nation's largest electric utilities, provided a private plane for Domenici's trip back to Washington. An official in the company's government relations office rode back to the capital with the senator, Exelon spokeswoman Jennifer Medley said.

Marnie Funk, communications director of the Energy and Natural Resources Committee, said Domenici gave two speeches during his trip to Arizona -- one to the conference of utility company chief executives and the other to a nearby convention of western business interests. "Between speeches, he held several meetings with utility executives who wanted to discuss some industry concerns," Funk said, adding that the trip complied with Senate rules.

In addition to the travel for Lugar, the Aspen Institute, a nonprofit group that aims to foster dialogue among leaders, paid for several international flights for his wife, Charlene, and for five-night hotel stays by the two in Venice and Geneva. Lugar's press secretary, Andy Fisher, said the trips were to conferences in which lawmakers of both parties met all day with experts and conducted discussions about how to turn ideas into legislation.

Durbin was one of the Senate's most frequent international fliers. He also reported taking a six-day trip to Cape Town, South Africa, for a conference on international affairs and "fact finding trip," paid for by the Chicago Council on Foreign Relations and the South African Institute of International Affairs.

Durbin's office said he took one trip that was not reported on the disclosure form, because the paperwork on it had been misfiled. Durbin took a trip to India and Bangladesh Feb. 13 to 21, 2004, paid for by Results, a nonprofit poverty and hunger group.

Durbin's communications director, Joe Shoemaker, said the purpose of the trip was to study AIDS, microcredit loan programs and the role of women in government in that part of the world.

Durbin said through his communications director that the trips made him a better and more engaged legislator, and gave him a passion for issues he would never have dreamed of otherwise.

"I believe every member of Congress should have to explain why they don't travel at least once a year to an important place," Durbin said.

Durbin said he favors trips put on by nonpartisan public policy groups, rather than by private concerns. "The trips allow members to immerse themselves in a single issue for several days, and they don't push a particular political agenda," he said through Shoemaker.

Sen. Debbie Stabenow (D-Mich.) said the Aspen Institute covered a trip -- including transportation, lodging and meals -- to Barcelona to attend a conference on what her disclosure report called "political Islam." She also reported that the American Sugar Alliance covered her expenses for a speaking engagement in Vail, Colo.

Sen. George Allen (R-Va.), gearing up for a potential 2008 presidential bid, was paid for travel and lodging to attend the Consumer Electronics Association convention in Las Vegas in January 2004. He reported family assets of $1.2 million to $3.3 million, a mortgage on a commercial rental property of $50,001 to $100,000, and land including 98.5 acres in Albemarle County.

Sen. Barbara A. Mikulski (D-Md.) spent 20 expenses-paid days in Honolulu to attend an Aspen Institute conference. Sen. Paul S. Sarbanes (D-Md.) was reimbursed for travel to attend five board of trustees meetings at his alma mater, Princeton University, in New Jersey; to address the Economic Club of New York and to be inducted into the American Academy of Arts and Sciences in Cambridge, Mass.

The disclosure forms also highlighted the many ways senators can enlarge their household incomes, from book contracts and royalties to fees for spouses' service on corporate boards to a song-writing agent for Sen. Orrin G. Hatch (R-Utah).

Books -- written or planned -- are a major source of outside income for senators. Sen. Hillary Rodham Clinton (D-N.Y.) reported royalties of $2,376,716 for her bestseller, "Living History." She reported royalties of $10,012 for an earlier book, "It Takes a Village," which were donated to charity, according to the form.

Clinton's form showed that she and former president Bill Clinton have paid off the millions of dollars they owed in legal fees. The report also showed a dramatic drop in the former president's speaking income in 2004, when he was promoting his book and underwent heart surgery.

The former president's spokesman, Jim Kennedy, noted that Clinton does not receive compensation for many appearances. "He's more in demand than ever, but most requests have to be turned down," Kennedy said.

Sen. Barbara Boxer (D-Calif.) reported a $15,938 advance for a novel due out in the fall. Sen. Elizabeth Dole (R-N.C.) reported a publishing agreement but no specific book plan. Sen. Trent Lott (R-Miss.) listed a book advance for $57,613 and Sen. Kay Bailey Hutchison (R-Tex.), gearing up for a run for governor, reported a 2003 book contract for $66,667.

Among unusual sources of outside income was the obstetrics practice of Sen. Tom Coburn (R-Okla.), who petitioned the ethics committee to allow him to continue receiving medical income. He reported receiving more than $260,000 from Thomas A. Coburn, MD Inc. and Muskogee Allergy Clinic Partnership.

Most reports were a dozen pages or so, stapled in a corner. But Sen. John F. Kerry (Mass.), last year's Democratic presidential candidate, has such extensive holdings that his form was 73 pages long and was secured by a rubber band.

Research editor Lucy Shackelford and staff writer Spencer S. Hsu contributed to this report.

A nonprofit group paid the expenses of Sen. Debbie Stabenow (D-Mich.) for a conference on Islam in Spain. Three utility companies paid expenses for a trip to Arizona by Sen. Pete Domenici (R-N.M.).