U.S. President Donald Trump took to Instagram on Tuesday to express his support for Prime Minister Benjamin Netanyahu, reposting a picture that the premier posted on his own account which features a campaign billboard in which he is seen smiling and shaking hands with Trump.

The billboard reads: "Netanyahu. In Another League," and is the latest instance in which the Israeli prime minister boasted of his connection with Trump as part of his election campaign ahead of the April 9 ballot.

Trump reposting Netanyahu's Instagram photo of his election billboard

A senior White House official denied later on Tuesday that the Instagram post is a political endorsement, adding that the Trump administration is not endorsing any candidate in the upcoming election.

"It's no secret that President Trump and Prime Minister Netanyahu have a strong relationship based upon mutual respect and that they reflect the mutual admiration and affection of the American and Israeli people," the official noted.

Another display of the Netanyahu-Trump ties recently emerged in the form of a campaign video that showed Netanyahu declaring at a cabinet meeting that the U.S. Embassy must be moved to Jerusalem, and ended with Trump announcing the Jerusalem embassy's official opening.

Trump's hard-line stances on Iran, the Palestinians, and the embassy move have earned him fans in Israel – one of the few nations where Trump ties help rather than hinder in the political arena. Netanyahu has been relying heavily on the idea that his ties with and influence on the president can't be matched by another candidate.

The Instagram post isn't the first time Trump has seemingly backed Netanyahu in an election. In 2013, Trump released a video calling the prime minister “a terrific guy” and a “terrific leader” for Israel. “He’s a winner, he’s highly respected, he’s highly thought of by all.”

Such an open display of support by a U.S. president for an Israeli prime ministerial candidate is unprecedented.

In the past, it has usually been Republicans who have slammed Democratic presidents for interfering in Israeli election campaigns, attempting to tip the scales for their favored candidate.

President Barack Obama was criticized in 2015 for butting heads with Netanyahu ahead of his famous congressional address opposing the Iran deal – an attempt to send a message that voting for him would further damage the U.S.-Israel relationship. That move was seen to have backfired, instead raising the prime minister’s status for standing up to the U.S. president.

The Obama White House was accused of stealthily fueling the anti-Netanyahu organization V15, which unsuccessfully attempted to unite the political forces that would unseat the Israeli prime minister using the strategies that helped elect Obama. V15 was guided by Jeremy Bird, the national field director of Obama’s 2012 presidential campaign.

In 1996, following the assassination of Yitzhak Rabin, President Bill Clinton was perceived to be strongly hoping for a Labor Party victory. In an interview last year, Clinton was asked whether he “tried to help Shimon Peres to win the election.” He replied: “That would be fair to say. I tried to do it in a way that didn’t overtly involve me.”

Without offering specifics, Clinton said, “I did try to be helpful to [Peres] because I thought he was more supportive of the peace process. And I tried to do it in a way that was consistent with what I believed to be in Israel’s interest.”