JERUSALEM — A growing rift between Prime Minister Benjamin Netanyahu and his defense minister, Ehud Barak, a political rival, centers on Israel’s strategic relations with the United States as Mr. Barak tries to turn the tension between Mr. Netanyahu and Washington to his political advantage.

After years of a close alliance during which the pair almost exclusively directed Israel’s campaign against Iran’s nuclear program, Mr. Netanyahu and Mr. Barak have been trading the kind of barbs that would appear, at least for now, to mean an end to that kind of intimate cooperation.

Underlying the argument is a competition over who can best steer Israel’s Iran policy and other national security mainstays like the Palestinian issue. Those differences, while not new, are coming to the forefront now because Mr. Netanyahu may soon call for early elections, perhaps scheduling a vote for February.

Just weeks after Mr. Netanyahu was perceived by critics as having meddled in America’s presidential election by criticizing President Obama’s approach to Iran, the Israeli leader’s strained relations with Washington are emerging as a hot electoral issue in Israel. Israelis are anxious about the prospect of an attack on Iran without close American coordination, and they generally view strong ties with the United States as crucial, framing Mr. Netanyahu’s clash with the White House as a rare political weakness.

“Barak understands that elections are on the horizon,” said Shmuel Sandler, a politics and foreign policy expert at the Begin-Sadat Center for Strategic Studies at Bar-Ilan University. “He wants to separate himself from Netanyahu. What is his claim to fame? That he has good relations with Washington.”

On Wednesday, Mr. Netanyahu’s loyalists accused the defense minister of using his recent trip to the United States to differentiate himself from the prime minister and move away from the recent friction with the Obama administration.

“As far as I know, yes, he distanced himself in an attempt to make political gains,” Yisrael Katz, the minister of transportation, told Israel Radio.

Mr. Katz was echoing remarks attributed to Mr. Netanyahu from a closed meeting on Tuesday. Mr. Netanyahu was quoted in the Israeli news media as saying that Mr. Barak had deliberately exacerbated the tensions between the prime minister and Washington in an attempt to make himself look like the moderate who can repair relations.

In response, Mr. Barak’s office issued a statement saying that the defense minister “works to strengthen relations with the United States and at their heart, the security relationship.”

“The importance of the special security and intelligence relations built up over the past five years during which Barak has served as the minister of defense should not be forgotten,” the statement added. “Those special relations contribute directly to the security and interests of Israel.”

Critics said that Mr. Netanyahu and his supporters were trying to deflect blame for the bad blood between the prime minister and Mr. Obama.

“Barak was trying to calm the waters while Netanyahu was making statements that raised the temperature,” said Shlomo Avineri, a professor of political science at the Hebrew University of Jerusalem. The prime minister has grown “uncomfortable,” he said, with the image of Mr. Barak as “the responsible adult.”

Israeli general elections are scheduled for October 2013, but Mr. Netanyahu has made it known that if he cannot reach agreement with his coalition partners on what he calls a “responsible” budget within 10 days, he will call an early vote.

Nahum Barnea, a columnist at the newspaper Yediot Aharonot, wrote Wednesday that the budget has a shortfall of nearly $4 billion and that the only way to cover it is by a significant cut in the defense budget, since alternatives like raising taxes or cutting services cannot be done in an election year.

“There is nothing personal in Netanyahu’s offending statements against Barak,” Mr. Barnea wrote, adding that the background to the dispute was “only politics.”

Mr. Netanyahu leads the conservative-leaning Likud Party while Mr. Barak, a former Labor Party leader long unpopular with the electorate, leads the tiny, centrist Independence faction. Recent polls indicate that Mr. Netanyahu remains unrivaled as a contender for the post of prime minister, while Mr. Barak’s party is struggling to cross the electoral threshold for a seat in Parliament.

But in the Israeli multiparty political system, leadership also depends on the art of coalition building.

According to political experts here, Mr. Barak had wanted a guarantee from Mr. Netanyahu that he would continue to serve as defense minister in the next government, but there was strong opposition from within Mr. Netanyahu’s party.

Instead, Mr. Barak has been trying to carve out an agenda of his own to appeal to voters. With the Israeli-Palestinian peace negotiations long stalled, he recently proposed a unilateral plan for creating a separate Palestinian state that would have Israel annexing parts of the West Bank and withdrawing from others.

Most pointedly, though, he has been accentuating his relationship with the Americans. He has praised American preparedness for dealing with Iran and, after Mr. Netanyahu infuriated the Obama administration by demanding that it set so-called red lines on Iran, Mr. Barak issued a statement saying that differences between Israel and the United States on such a critical issue should be worked through “behind closed doors.”

Underscoring their shared security interests, the two countries are scheduled to hold a joint military exercise next month to practice the defense of Israel against long-range missile attack.

When Mr. Netanyahu was voted in, part of his appeal was his familiarity with the workings of Washington and his ability, as some here say, to “speak American.”

But when it comes to the Israeli electorate and relations with the United States, Mr. Avineri of the Hebrew University said, “There is a complexity.”

“On one hand, Israelis like leaders who stand up to the Americans, but on issues of national consensus within Israel,” he said. “On the other hand, they do not like a leader manufacturing a crisis on an issue where there is probably no reason to create a crisis.”