WASHINGTON — Richard Lugar was never considered to be one of Israel’s leading advocates on Capitol Hill.

The veteran Republican senator from Indiana, who suffered a primary defeat last week after 35 years in office, is famously his own man.

Lugar, the top Republican on the Foreign Relations Committee, consistently backed defense assistance for Israel and in the 1980s championed freedom for Soviet Jews. But he was also known for pushing a more active U.S. approach to brokering Middle East peace than that favored by much of the pro-Israel lobby, and he preferred to move ahead cautiously on Iran sanctions.

Yet pro-Israel groups ponied up when Lugar came calling as it became clear that a Tea Party candidate was threatening to unseat him, lending logistical and financial support.

Israel advocates and GOP insiders explained that Lugar represented a breed of lawmaker who pro-Israel groups see as valuable to their cause and disappearing: One who reaches across the aisle.

“Lugar wasn’t actively pro-Israel, but he wasn’t anti either,” said Mike Kraft, a staffer on the Senate Foreign Relations Committee in the 1970s and 1980s who now is a consultant on counterterrorism and writes for a number of pro-Israel websites and think tanks. “But generally losing a good, balanced, thoughtful guy on foreign policy is a real tragedy. It weakens the American political system.”

Lugar received $20,000 from NORPAC, a leading pro-Israel political action committee based in New Jersey — the most of any candidate this cycle.

“We sent extra money to Lugar because he called and asked,” said Ben Chouake, NORPAC’s president.

Chouake acknowledged that Lugar, 80, was “never the most” pro-Israel member of Congress, “but sometimes you have to back someone because of who a person is.” He was referring to the Indianan’s 36-year career in the Senate and his reputation for getting Democrats and Republicans to work together.

A pro-Israel political giver told JTA that Lugar also raised money from supporters of Israel at events in Indiana and New York City.

Ultimately it was for naught: Richard Mourdock, Indiana’s state treasurer, easily defeated Lugar in the May 8 GOP primary by a margin of 61-39 percent. Mourdock now faces Rep. Joe Donnelly (D-Ind.) in the general election.

Mourdock campaigned on a platform that opposed compromise.

“I have a mind-set that says bipartisanship ought to consist of Democrats coming to the Republican point of view,” he told the Fox News Channel.

Matthew Brooks, the Republican Jewish Coalition’s executive director, said that Lugar’s defeat had more to do with his particular vulnerabilities — he famously has not lived in his home state since the 1970s — than with any larger trend toward uncompromising partisanship in the party.

“No matter how long you’ve been in office, politics starts at home — and maybe it would be a good idea to have a home in the state,” Brooks said.

A pro-Israel donor said that his fellow givers were now focused on preserving the career of Sen. Orrin Hatch (R-Utah), who also is facing a Tea Party insurgent in next month’s primary.

While some Israel Republicans are rooting for the establishment GOP incumbents, it is not because their Tea Party opponents are hostile to Israel.

Indeed, the Tea Party wave of 2010 has turned out to be pronouncedly pro-Israel, with the exception of Sen. Rand Paul (R-Ky.), who says he would end assistance to Israel as well as all foreign aid. Pro-Israel insiders single out Sen. Mike Lee (R-Utah), a Tea Partier who ousted Robert Bennett, as a star of that class. Mourdock himself backed Israel Bonds as Indiana treasurer and has initiated outreach to the pro-Israel community.

The problem, the insiders say, is not one of enthusiasm for Israel but in how members of the party’s right wing have proposed changing the mechanisms for allocating foreign aid.

The American Israel Public Affairs Committee has always emphasized the importance of backing the entire foreign assistance package. The logic is multifold: Aid overall builds good will for the United States and its allies; the perception that aid to the developing world is inextricable from aid to Israel promotes good will for Israel in those countries; singling out Israel for assistance while neglecting other countries promotes unseemly stereotypes about Jewish influence; and cutting aid inevitably will likely lead to cuts in assistance for Israel, however much the current Congress supports the country.

“They want to cut everything but Israel, but in the end, if everything else is cut, assistance to Israel will have to be cut,” said the pro-Israel donor.

Marshall Breger, President Ronald Reagan’s liaison to the Jewish community, predicted that as Tea Party conservatives gain in strength, the pro-Israel community may have to work out a formula — first proposed in a 2010 interview with JTA by Rep. Eric Cantor (R-Va.), now the majority leader — whereby Israel assistance is treated separately from foreign assistance.

“When the thinking is going to be, ‘do you want to make a special exception for Israel or do you want to drop foreign aid for Israel?’ AIPAC will likely say ‘special exception,’ ” said Breger, who is now a law professor at the Catholic University in Washington.

More intangibly — but equally as critical — is how polarization has corroded bipartisanship in Congress, said Jason Isaacson, the legislative director for the American Jewish Committee. Even with overwhelming support for Israel, the failure of the parties to forge compromises on foreign policy undercuts America’s international profile — and that’s not good for Israel, he said.

“Because of the commitment of a great many people over a long period of time, support for Israel is a deeply entrenched nonpartisan sentiment,” Isaacson said. “What I do see under stress is the ability of either Congress or the executive branch to work together to pursue a consensus foreign policy.”

A senior GOP congressional staffer who supported Lugar conceded that Mourdock, albeit within his limited public experience as a state treasurer, has been more unequivocal in his support for Israel than Lugar had been.

“The statements that Mourdock has made that are troubling are less on policy and more on bipartisanship and working across party lines,” said the staffer. “We haven’t demonized each other enough? That sort of ideology isn’t just a problem for centrists, it’s a problem for anybody who wants to get something done.”

Morris Amitay, a former AIPAC executive director who now heads Washington PAC, a pro-Israel political action committee, said the failure to compromise, which he blamed on both parties, was undermining the U.S. profile internationally.

“Sometimes I long for the days of the Cold War,” said Amitay, who first worked as a congressional staffer in 1969. “Now extremes at both ends have more influence than they should. We’ve got problems in Latin America, Africa, especially northern Africa, Russia won’t cooperate — and Congress can’t function.”