WASHINGTON — American politicians like to pick and choose when they'll abide by the storied notion that politics should stop at the water's edge — and when to give that idea a kick in the pants.
The doctrine, which dates back to Daniel Webster's time, holds that as much as Americans may debate foreign policy among themselves, they should keep those arguments within the family and speak with one voice abroad.
That concept has tread marks running all over it right now, as congressional Republicans raise a global ruckus over the Obama administration's negotiations on a deal aimed at keeping Iran from developing nuclear weapons.
First, Republican leaders did an end run around the White House to invite Israeli Prime Minister Benjamin Netanyahu to speak in opposition to the negotiations before a joint meeting of Congress earlier this month. And then 47 GOP senators upped the ante by sending Iran's leaders a letter this week warning that any agreement with President Barack Obama's administration could expire the day he leaves office.
Democrats were livid, especially about the letter, calling it stunning, provocative, offensive and more. But they've had their own run-ins with stepping over the water's edge in recent years when asserting themselves on foreign policy. And there has even been finger-wagging between fellow Republicans over how the sentiment should be properly observed.
—In April 2007, President George W. Bush complained that a trip by House Speaker Nancy Pelosi and other Democrats to Syria that included a visit with President Bashar Assad was counterproductive and had sent mixed signals to the Syrian government, which his administration accused of terrorism.
—In September 2002, Rep. Jim McDermott of Washington and two fellow Democratic congressmen traveled to Baghdad to push for continued weapons inspection in Iraq rather than war. "The American people are not with one voice on Iraq, and they are debating about it like the rest of the world," McDermott said. Critics called them traitors and dupes of Saddam Hussein.
—In November 1987, House Speaker Jim Wright was accused by the Reagan administration of meddling in foreign policy when he attended a meeting between Nicaraguan President Daniel Ortega and a Catholic cardinal in Washington where Ortega outlined a cease-fire plan to end Nicaragua's six-year war with U.S.-financed Contra rebels.
Both Obama in 2008 and Mitt Romney in 2012 made foreign trips as presidential candidates that were replete with implied criticism of the sitting presidents. And Romney, for his part, got a scolding from within his own party in March 2012 for criticizing Obama's remarks on missile defense policy while the president was still abroad.
"Clearly, while the president is overseas ... I think it's appropriate that people not be critical of him or our country," House Speaker John Boehner said at the time.
It's all a far cry from the days when Republican politician James Montgomery Beck, a vocal critic of President Woodrow Wilson's foreign policy, said in London in 1916, "if I shall ever be tempted to criticize in a public gathering in a foreign land either the president of the United States or the government of the day, may my tongue cleave to the roof of my mouth!"
Or the times of Senate Foreign Relations Committee Chairman Arthur Vandenberg, a Republican who became a symbol of bipartisanship in 1947 when he turned from isolationism to support Democratic President Harry Truman on major post-World War II foreign policy moves, asserting that it was time to stop "partisan politics at the water's edge."
The "water's edge" concept largely held sway through the tensions of the Cold War, says Senate Historian Donald Ritchie, but ran into trouble when people began having doubts about the government's actions and pronouncements on Vietnam.
The war left President Lyndon Johnson convinced that supporters of his successor, Richard Nixon, had tried to persuade the South Vietnamese government not to join the Paris peace talks until after the election by arguing they would get a better deal under a Republican president. Those secret communications, which Johnson labeled "treason," went far beyond anything today's Republicans have attempted to do in the open.
As the Vietnam War dragged on, says Ritchie, "There was no longer automatic support of what the president was going to do."
Still, former Sen. Richard Lugar, an Indiana Republican who chaired the Senate Foreign Relations Committee from 2003 to 2007, says he always tried to find a way to build consensus at least on votes coming out of his committee.
"I took the position that America's face to the rest of the world should not be a 9-to-8 vote," he said, adding that he sees the committee's current chairman and ranking Democrat striving for bipartisanship, as well. The GOP senators' letter, he said, was "not helpful, and I'm hopeful that it did not create any particular harm."
Robert Lieber, a professor of international affairs at Georgetown University, said that as the national political scene has become more polarized in recent years, the "tendency to be more velvet-gloved on foreign policy" is waning.
Politicians still invoke the idea, though, when it works to their advantage. Wisconsin Gov. Scott Walker, a potential GOP presidential candidate, used it to fend off a question about the Islamic State group during a recent trip to London.
"I don't think it's polite to respond on policy in the United States when you're in a foreign country," he said.
Often, it depends on who's in power and who's not, says James Lindsay, director of studies at the Council on Foreign Relations.
"If your party holds the presidency, you very much insist on the importance of speaking with one voice," he says. "And when you're out of power, you talk about the importance of dissent, of speaking truth to power, of the miracle of democracy, which puts even the most significant of questions to public debate."
Associated Press news researcher Jennifer Farrar contributed to this report from New York. Follow Nancy Benac on Twitter at http://twitter.com/nbenac.