An American political ad released on YouTube over the weekend endorses Israeli Prime Minister Benjamin Netanyahu’s contentious upcoming speech in Washington and attacks former US secretary of state Hillary Clinton for her alleged lack of support for the Israeli leader.

The ad was financed by “The Emergency Committee for Israel,” a group founded by William Kristol, the Jewish-American editor of the neoconservative Weekly Standard magazine.

The video starts by criticizing President Obama for holding “secret talks” with Iran and accuses the US leader and “anti-Israel Democrats” of boycotting Netanyahu during his visit to Washington next week.

It then asks why Clinton has not commented on the issue. As the apparent front-runner for the Democratic nomination for president in 2016, the ad asks: “Where is Hillary Clinton? Does she support the boycotters or is she too afraid to stand up to them?”

The New York Times reported that the ad will be televised, mainly on cable networks, with a relatively modest budget of $200,000.

Both the White House and Clinton’s offices did not comment on the ad.

“The Obama administration has launched an all-out assault against the Israeli prime minister,” Noah Pollak, the executive director of the Emergency Committee for Israel, said in a statement quoted by the Times.

“Friends of the Jewish state ranging from Joe Lieberman to Elie Wiesel to Shelley Berkley have rallied to his defense. Hillary Clinton has remained silent. It’s time for the former secretary of state and prospective presidential candidate to come out of hiding and tell us where she stands. Does Hillary Clinton stand with the boycotters or the supporters of Israel?” Pollak added.

The prime minister is speaking to Congress at the request of Republicans. His visit was coordinated without the Obama administration’s knowledge, deepening tensions between two leaders who have never shown much affection for each other.

Jeremy Ben-Ami, president of the liberal Jewish advocacy group J Street, said Netanyahu was “crossing some lines that haven’t been crossed before and is putting Israel into the partisan crossfire in a way it has not been before.”

Nearly a dozen Democratic lawmakers plan to sit out Netanyahu’s speech, calling it an affront to the president.

Stopping Iran from building a nuclear bomb has become a defining challenge for both Obama and Netanyahu, yet one they have approached far differently.

For Obama, getting Iran to verifiably prove it is not pursuing nuclear weapons would be a bright spot in a foreign policy arena in which numerous outcomes are uncertain and would validate his early political promise to negotiate with Iran without conditions.

Netanyahu considers unacceptable any deal with Iran that doesn’t end its nuclear program entirely and opposes the emerging deal as one that fails to effectively tackle what he considers an existential threat to Israel.

Obama has refused to meet Netanyahu during his visit, with the White House citing its policy of not meeting with foreign leaders soon before their elections.

Jewish House Democrats personally offered Netanyahu a chance to lower the political temperature after he accepted a Republican invitation to speak to Congress next week on Iran — a less provocative, closed-door session. Netanyahu, however, turned them down, arguing that to do so would be partisan, frustrating members of Obama’s party who are caught between the White House and the Israeli leader.

The prime minister is to meet after his speech with a bipartisan group of legislators.

House Speaker John Boehner has defended his invitation to Netanyahu, saying Americans need to hear from Netanyahu.

AP contributed to this report.