Opposition politicians are charging that Netanyahu — who has publicly confronted Obama over policy toward Iran and peace efforts with the Palestinians — is jeopardizing Israel’s long-standing alliance with the United States.

Netanyahu, who as head of the right-leaning Likud party plans to campaign on a platform of safeguarding Israel’s national security, has made several conciliatory gestures toward Obama in the days since the U.S. election, in an apparent effort to smooth over differences.

On Thursday, Netanyahu called Obama to congratulate him and pledged to “continue working together.” On Wednesday, he summoned the American ambassador to Israel, Dan Shapiro, for a televisedcongratulatory meeting and declared that security relations between the two countries were “rock solid.”

Responding to his critics, Netanyahu charged Thursday that they were making a futile effort to “stir up trouble between us and the United States” and said that the two nations’ alliance remained strong.

Still, in an election that is likely to also be a referendum on his threat to attack Iran’s nuclear facilities, Netanyahu’s campaign now has a weak spot, according to several analysts.

“Netanyahu is vulnerable on national security and foreign policy, because the opposition will argue that given his bad relationship with Obama and given the need to make critical decisions about Iran in the spring or the summer, he should be replaced,” said Eytan Gilboa, an expert on U.S.-Israeli relations at Bar-Ilan University.

Netanyahu publicly challenged Obama in September to take a more aggressive stance toward Iran, saying those who were not ready to draw “red lines” with Iran over its nuclear program did not have the “moral right” to prevent Israel from taking military action.

Obama’s call in May 2011 for a peace agreement with the Palestinians based on Israel’s 1967 borders got an icy reception from Netanyahu, who lectured Obama on the subject in the Oval Office. The two had clashed earlier over Israel’s settlement construction in the West Bank and East Jerusalem.

The two leaders’ tense relationship has invited comparisons to the rift between Prime Minister Yitzhak Shamir and President George H.W. Bush over Israeli settlement construction in the early 1990s. That diplomatic showdown set the stage for Shamir’s subsequent electoral defeat.

Ehud Olmert, a former prime minister who is weighing a political comeback as the head of a centrist bloc even as he faces an appeal of his acquittal on corruption charges, told Jewish leaders in New York on Wednesday that Netanyahu had become a liability in relations with Washington.

“Following what Netanyahu has done in the last few months, the question is whether our prime minister has a friend in the White House,” Olmert said, according to an account from an aide that was published in Israeli media. “I am not sure of that, and it could be very significant to us at critical points.”

Yitzhak Herzog, a lawmaker from the left-of-center Labor Party, predicted that the lack of close relations between Obama and Netanyahu at a time of approaching “fateful decisions” will be “a problem for Netanyahu in the public.”

Shaul Mofaz, leader of the centrist Kadima party, told the Israeli television station Channel 2 that Netanyahu had “definitely caused damage” by seeming to bet on a Romney victory. “I think that a prime minister in Israel doesn’t do two things,” Mofaz said. “He doesn’t interfere in the elections in the U.S. and he doesn’t gamble on one of the candidates.”

Yet many of Netanyahu’s backers in Israel argue that the source of the problem is what they call Obama’s cool stance toward the prime minister, who they say is simply defending the country’s vital interests.

Abraham Diskin, a political scientist at the Hebrew University of Jerusalem, said the opposition’s focus on relations with the United States is a “double-edged sword.” While Israelis value those ties, Diskin said, many have rallied behind Netanyahu in times of confrontation and believe that he has emerged with the upper hand.

Some Israeli commentators have speculated since Obama’s victory that he might repay Netanyahu in kind by indirectly endorsing his opponents in the Israeli election or take a tough line on advancing peace efforts with the Palestinians. Others predict that the chill in relations will only deepen.

“The American commitment to Israel’s security and continued existence will not change,” wrote Sima Kadmon, a columnist for the widely circulated Yediot Ahronot daily. “But regarding anything beyond that — there will be a cold shoulder.”