A leading Republican moderate with a foreign policy background endorsed presidential candidate Barack Obama on Tuesday as the Democrat sought to show his appeal to members of both political parties.

Former Rep. Jim Leach of Iowa was among Republicans the Obama campaign said were crossing party lines to support Obama. The Illinois senator’s campaign said he was also being backed by the Republican mayor of Fairbanks, Alaska, Jim Whitaker. The campaign did not release the names of other GOP supporters or the size of the group.

“I’m convinced that the national interest demands a new approach to our interaction with the world,” Leach, a foreign service officer before being elected to Congress, said in a conference call with reporters.

Leach predicted that many Republicans and independents would be attracted by Obama’s campaign but said his decision to endorse a Democratic presidential candidate for the first time wasn’t easy.

“Part of it is political parties are a distant analog to families and you really hate to step outside a family environment,” Leach told The Associated Press in an interview.

Wendy Riemann, a spokeswoman for Republican candidate John McCain, responded that it was ironic that Leach, who supported campaign finance reform, would back Obama, who has opted out of public financing.

“A single endorsement does not hide the fact that Sen. Obama has no record of achievement beyond the confines of his party,” Riemann said in a statement. “While John McCain has spent his career putting the country first — ahead of personal and party interests — Sen. Obama’s record is a lesson in partisanship.”

Leach, 65, was elected to Congress in 1976 and served 30 years before losing a re-election bid in 2006. As a moderate, he was often at odds with the conservative GOP leadership.

“For me, the national interest comes before party concerns, particularly internationally,” said Leach, who has long been an opponent of the war in Iraq.

“We do need a new direction in American policy, and Obama has a sense of that,” he said. “He recognizes that a long-term occupation of Iraq is not only expensive, it’s extremely dangerous to the American interests.”

Leach said he was attracted to Obama’s call for a dialogue with nations such as Iran that have long been seen as U.S. adversaries.

“He also recognizes that it’s preferable to speak with potential adversaries rather than simply shun them,” Leach said.

Leach’s decision could cause ripples with the group Common Cause, where he serves on the board and which has a policy against political endorsements. Leach said he wasn’t aware of any concerns by the nonpartisan group, which supports accountability in government.

Many Republicans argue that McCain has an edge when the debate turns to foreign policy because of his long experience in dealing with such issues and his record as a career military officer and prisoner of war.

“There’s a distinction between trumpeting issues and realistically looking at effectiveness,” Leach said. “I have never known a time period where the American brand has been in less repair.”