There are many ways to test a friendship in life. In politics there is really only one.

When U.S. Sen. Ted Stevens was indicted by a federal grand jury two years ago for failing to disclose gifts from an Alaska oil services executive, U.S. Sen. Daniel Inouye, his friend for more than four decades, could have put some public distance between himself and the Alaska Republican.

The Hawaii Democrat had already defied his party by raising money and campaigning for Stevens’ re-election in Alaska during the federal investigation. Inouye could have easily stepped back. Instead, he testified as a character witness at Stevens’ trial. He issued a written statement just before the election, after Stevens had been convicted and some GOP leaders were urging him to resign, expressing absolute confidence that Stevens would be exonerated on appeal.

Partisans — especially today, when party lines are drawn so sharply — have sometimes had trouble understanding a bond that began in the late 1960s among two young senators from faraway states and which lasted through Stevens’ death in a plane crash Monday night in Alaska.

"We had the unbelievable chore of trying to convince our colleagues that we were part of the United States and worthy to be called Americans," Inouye recalled in an interview in 2007. "Ted and I were involved in this type of battle from day one."

Inouye and his wife, Irene, released a statement yesterday extending their thoughts and prayers to Stevens’ wife, Catherine, and his family. The senator described their friendship as a special one. He said they disagreed more than they agreed on public policy but always worked together for Hawaii and Alaska.

"I have lost my brother," he said.

The alliance between Inouye and Stevens, which grew in strength as the two became among the most senior members in the Senate, helped ensure that they could secure federal spending for their home states no matter which party controlled Congress and the White House. The partnership also extended to home-state public-policy issues. Inouye was among the few Democrats who supported oil drilling in the Arctic National Wildlife Refuge in Alaska. Stevens was one of the few Republicans who backed native Hawaiian federal recognition.

One of Inouye’s disappointments is that when he finally took over as chairman of the Senate Appropriations Committee last year, Stevens would not be his partner. Stevens lost re-election after his felony conviction, which was later dropped for prosecutorial misconduct.

Jeff Watanabe, an attorney and Inouye confidant, called the friendship remarkable. He recalls briefing a staffer for Stevens in Washington about a commerce issue when the staffer asked where Inouye stood. Watanabe told the staffer that Inouye was behind the issue, and continued with his briefing, but he was soon cut off. "You can stop," the staffer told him. "My senator and your senator are brothers. If your senator says it’s OK, it’s OK."

Watanabe said it is difficult to imagine a similar public friendship given today’s partisanship. "It was probably the kind of relationship that no longer exists in the U.S. Senate, or anywhere else for that matter," he said.

U.S. Sen. Daniel Akaka, D-Hawaii, said Stevens will be missed. "He was a friend of Hawaii and he understood the United States’ responsibility to its indigenous people," he said in a statement. "He was a dear friend. We were ohana."

Former U.S. Rep. Neil Abercrombie called the Hawaii and Alaska alliance "profound."

"It’s a terrible blow, both to Hawaii as a state and, of course, personally to Sen. Inouye," he said.

Gov. Linda Lingle, a Republican, also offered her condolences to the Stevens family. "Sen. Stevens was a true patriot who loved his country and his home state," she said in a statement. "He was also a friend to Hawaii and a supporter of federal recognition for native Hawaiians."