WASHINGTON—There will be the speeches, and they will resound like an echo. And then there will be the talk.

When President Barack Obama speaks on March 4 to the American Israel Public Affairs Committee, and when Israeli Prime Minister Benjamin Netanyahu addresses the group the following day, expect many of the same catchphrases to carry over: A nuclear Iran is unacceptable. Israel and the United States stand together.

The quesion is, how much of the comity will carry over into the private chat that Netanyahu and Obama share on March 5. They will be meeting the same day as Netanyahu’s speech to AIPAC’s annual forum, which is expected to attract a record-setting 11,000 to 13,000 activists to the cavernous Washington Convention Center.

Depending upon who is talking and their political affiliation, the two leaders either are marching in lockstep in their Iran plans or they are on opposite sides of a significant gap.

“I cannot think of any issue on which we are better coordinated than on the issue of Iran,” U.S. ambassador to Israel Dan Shapiro told the annual meeting of the Conference of Presidents of Major American Jewish Organizations on Feb. 23 in Jerusalem.

But days earlier, after meeting with Netanyahu, U.S. Sen. John McCain (R-Ariz.) said there was “daylight” between the two nations when it came to confronting Iran.

“There should be no daylight between America and Israel in our assessment of the threat,” said McCain, who was leading a delegation of GOP senators to the region. “Unfortunately there clearly is some.”

McCain’s assessment followed a warning during a Feb. 19 CNN interview with Martin Dempsey, the chairman of the U.S. Joint Chiefs of Staff, who said that an Israeli strike would be “destabilizing.” It also comes as the frequency of meetings between top Israeli and U.S. security officials have intensified; the White House made a point last week of announcing that talks this week between Tom Donilon, the national security adviser, and Netanyahu, focused on Iran. This week, Ehud Barak, Israel’s defense minister, is visiting Washington to see his counterpart, Defense Secretary Leon Panetta, as well as Donilon.

McCain had signed onto a nonbinding resolution introduced last week that “strongly supports United States policy to prevent the Iranian Government from acquiring nuclear weapons capability.”

In fact, there is no such policy. Obama and his predecessors going back to the mid-1990s have sought to prevent Iran from acquiring a nuclear weapon. That differs from keeping Iran from achieving the capability to manufacture one, which has been Israel’s red line.

The resolution, which now has 35 co-sponsors, is expected to top the agenda of items that AIPAC activists will take with them to Capitol Hill on March 6, the conference’s last day.

The distinction between “acquisition” and “capability” is a critical one to the Netanyahu government, said David Makovsky, a senior analyst with the Washington Institute for Near East Policy.

Israel sees “capability” as a point of no return; in its view an Iran with the ability to put together a weapon within months would be game changer for the region, Makovsky said.

“The Israeli fear is in the North Korea experience of ‘too early, too early, oops, too late,’ ” he said, referring to that country’s development of a nuclear weapon despite years of Western efforts to dissuade it from making the leap from capability to possession.

In their presidential debates, Republican candidates have embraced the notion that Iran’s nuclear push could become irreversible sooner rather than later.

Netanyahu is likely to seek agreement from Obama on a red line that would come prior to Iran actually building a nuclear weapon, Makovsky said.

“There needs to be some convergence on the red lines of these two countries so they do not drift apart,” Makovsky said. “The need is to coordinate the clocks. This would reshape the elite policy debate in Israel over whether they should strike.”

One problem vexing such discussions is what, short of actually acquiring a nuclear weapon, could serve as a “red line.” One measure cited by a number of Iran watchers would be an ability to enrich uranium to 90 percent, which is weapons grade.

But such an enhanced capability is maddeningly hard to detect. An International Atomic Energy Agency analysis leaked last Friday to the news media said that on the basis of recent inspections and other intelligence, the agency had concluded that Iran tripled its production rate of uranium enriched to the level of 20 percent.

The report said that the increased production of the material was occurring at the underground Fordow enrichment facility near the city of Qom, and that if Iran chose to enrich the material to a 90 percent level, it would have enough nuclear material for four nuclear weapons.

In addition, the IAEA was concerned about the refusal of Iran to grant access to a military site, which the U.N. nuclear watchdog wanted to examine in order to ascertain whether the Islamic Republic was continuing to work on designing a nuclear weapon.

The IAEA said it was “unable to provide credible assurance about the absence of undeclared nuclear and activities in Iran, and therefore to conclude that all nuclear material in Iran is in peaceful activities.”

The Obama administration has led the intensification of sanctions in recent months, squeezing Iran’s economy to the extent that its unit of currency, the rial, has plunged in value.

But touting these sanctions might not be enough for the AIPAC crowd. One session at the conference is titled “Do sanctions work? Preventing a nuclear Iran.” It is billed in the conference program as follows: “Though the Iranian leadership has admitted that sanctions have hurt their country’s economy, the Islamic Republic continues to pursue a nuclear weapons capability.”

Tensions over whether sanctions suffice are likely to play out in other ways at the conference, which Panetta is also scheduled to address.

Gingrich, who is addressing the AIPAC conference on March 5, has been strongly critical of the Obama administration, even taking the rare step, for a politician, of taking the top U.S. military official to task.

Referring to Dempsey’s appearance on CNN, in which the chairman of the joint chiefs of staff described the Iranian regime as a “rational actor” that could be influenced by pressure short of a military strike, Gingrich at the Arizona debate said, “I can’t imagine why he would say that. And I just cannot imagine why he would have said it.”