A war is brewing on Capitol Hill. And while wars tend to create refugees, this one may result in fewer of them.

Sen. Mark Kirk (R-IL) is trying to get a handle on the real number of Palestinian refugees in the Middle East — a move that could result in a change of status for millions of Palestinians. His proposed language for the 2013 foreign appropriations bill would require the U.S. government to confirm just how many Palestinians currently served by the U.N. Relief and Works Agency — the body tasked with providing assistance, protection, and advocacy for Palestinian refugees — are actually refugees. The bill, slated for markup on May 22, would challenge the status of the children, grandchildren, and great-grandchildren of Palestinian refugees — a great many of whom claim to be refugees despite the fact that they were never personally displaced in the 1948 and 1967 Arab–Israeli wars.

The aim of this proposed legislation, Kirk´s office explains, is not to deprive Palestinians who live in poverty of essential services, but to tackle one of the thorniest issues of the Palestinian–Israeli conflict: the "right of return." The dominant Palestinian narrative is that all of the refugees of the Israeli–Palestinian wars have a right to go back, and that this right is not negotiable. But here´s the rub: By UNRWA´s own count, the number of Palestinians who describe themselves as refugees has skyrocketed from 750,000 in 1950 to 5 million today. As a result, the refugee issue has been an immovable obstacle in round after round of negotiations between the Israelis and Palestinians.

How have these numbers swelled, particularly as the Palestinians who fled or were forced from their homes in 1948 and 1967 grew old and died? This question lies at the crux of the Kirk amendment. And the answer is UNRWA.

The knock on UNRWA is that it exists to perpetuate the refugee problem, not solve it. It was UNRWA that bestowed refugee status upon "descendants of refugees," regardless of how much time had elapsed. As a result, the Palestinian refugee population has grown seven-fold since the start of the Arab–Israeli conflict. As one study projects, if descendants maintain their current status, the number of "refugees" in 2020 will be 6.4 million — despite the fact that few of the actual, displaced Palestinians will still be alive. In 2050, that number will reach 14.7 million.

UNRWA, which calls for a "just and durable" solution to the refugee problem, has unquestionably been a silent partner to the Palestinian leadership. The agency´s administration fully understands that if Israel accepted the PLO´s demand, it would be demographic suicide. As Palestinian Authority President Mahmoud Abbas himself has admitted, asking the Jewish state to repatriate 5 million Palestinians "would mean the end of Israel."

UNRWA´s warts notwithstanding, American taxpayers have rewarded it year after year. In the 2011 fiscal year, U.S. assistance to UNRWA stood at $249.4 million. Total contributions since its founding in 1949 amount to a staggering $4.4 billion.

In recent years, politicians and policy wonks, including one former UNRWA administrator, have called for UNRWA reform. The agency hasn´t merely demurred; it has girded for battle. UNRWA set up shop in Washington with two Capitol Hill–savvy professionals, despite the fact that its operations are entirely based in the Middle East, anticipating the need for what looks a full-scale lobby effort to defend its mission. The agency even toyed with changing its name last year in an attempt to burnish its image in the West.

UNRWA´s time to defend itself has unquestionably arrived. The Kirk amendment would require the secretary of state to report to Congress on how many Palestinians serviced by UNRWA are true refugees from wars past — those who could prove that they were personally displaced. That number is believed to be closer to 30,000 people. This new tally would then become the focus of America´s assistance to UNRWA for refugee issues.

Despite congressional Republicans´ current fervor to rein in America´s out-of-control debt, the bill´s proponents do not call for a full cutoff to the descendants. Rather, they seek to ensure that UNRWA services keep flowing to those who are needy. The United States would simply not view them as refugees — just people living in the West Bank or Gaza Strip and below the poverty line.

But funding for the future would not be guaranteed. As Kirk´s office explains, Congress will soon need to consider tough questions, like whether U.S. taxpayers should be footing the bill for welfare programs in the West Bank and Gaza Strip, or whether such services should be provided by the Palestinian Authority.

The fact that this language has made it to mark-up is nothing short of remarkable. The Israelis have historically avoided locking horns with UNRWA at all costs. In fact, they have quietly lobbied against UNRWA reform in the past. As one Israeli official confided, the Israel Defense Forces don´t want to risk being saddled with providing services to the refugees in the West Bank and Gaza Strip should UNRWA unravel. Indeed, one of the Israelis´ primary purposes in signing the Oslo Accords and supporting the creation of the Palestinian Authority was to ensure that they were no longer saddled with the responsibility of providing services to the Palestinians in the West Bank and Gaza Strip.

But today, with the peace process moribund, if not dead, the Israelis believe that UNRWA reform could serve as a defibrillator of sorts. By tackling one of the toughest challenges of the Palestinian-Israeli conflict without the bedlam that typically accompanies bilateral negotiations, there would theoretically be one less sticking point when the stars align again for diplomacy. Under the leadership of Knesset member Einat Wilf, this idea now has the backing of the Prime Minister´s Office, the Ministry of Defense, and the Ministry of Foreign Affairs.

In Washington, a coalition is still forming. Rep. Howard Berman (D- CA), the ranking member of the House Foreign Affairs Committee, broadly backs this idea but has yet to introduce language on the House side. However, bipartisanship may not be enough: The State Department, which pledged an additional $10 million in UNRWA in March, is expected to put up a fight. The legislation would undoubtedly anger some of Washington´s Arab allies, and Foggy Bottom tries to avoid that at all costs.

But such grumbling will likely pale in comparison to the expected outcry in the West Bank, Gaza Strip, and the Palestinian refugee camps in neighboring Arab countries. The refugee narrative is a sacred one in Palestinian political culture. Palestinian leaders will not simply table it because Congress passes new legislation. Rather, it´s a fair bet they will mobilize. When UNRWA merely mulled a name change in July 2011, Palestinians organized protests and sit-ins. Proposing real changes to UNRWA could even prompt violence.

In short, the Kirk legislation would strip Palestinian the descendants of their political symbolism. It would be a landmark for this generations-old conflict, but whether it paves the way for peace or conflict remains to be seen. There are few more potent symbols of the Palestinian cause. Don´t expect Palestinians to give it up easily.

This article first appeared in Foreign Policy.