UPDATE: This story was updated on Monday, May 14th at 4:20 p.m. with additional comment from Texas Sen. Ted Cruz.

WASHINGTON — Sen. Ted Cruz is hailing the controversial opening of the new American Embassy in Jerusalem as a positive step in long-elusive Middle East peace negotiations, as dozens were killed in deadly protests and critics slam President Donald Trump for abandoning decades-old U.S. foreign policy of remaining neutral.

"Recognizing Jerusalem as Israel's capital and relocating the U.S. Embassy sends a powerful message that America will stand by our friends and allies, and we will stand up to our enemies," Cruz said in prepared statement. "Moreover, it furthers the chances of peace in the Middle East by demonstrating that America's support for Israel is unconditional and will not be bullied by global media opinion."

His statements come as European and Arab leaders warn the U.S. is imperiling its chances of serving as a neutral arbiter in peace talks by siding with Israel in a bitter conflict.

The Texan, who has long advocated recognizing Jerusalem as the Israeli capital, is among several Republican senators and other American dignitaries attending the event on Monday. While there, he tweeted a series of photos depicting him with officials including White House senior advisers Ivanka Trump and her husband, Jared Kushner; other GOP lawmakers and former Connecticut Sen. Joe Lieberman, a Democrat-turned-independent.

Honored to be here in Jerusalem, the capital of Israel, on this historic day. Thanks for the photo, @IvankaTrump! pic.twitter.com/IAGUHFRhOY — Mike Lee (@SenMikeLee) May 14, 2018

The trip comes roughly five months after Trump formally recognized Jerusalem as the capital of Israel and announced plans to relocate the U.S. Embassy there from Tel Aviv.

Cruz, who last year signed onto legislation that would relocate the embassy, praised Trump's decision as "courageous and heroic." And on Monday, he tweeted that the facility is "breathtaking. Over 70 years in the making."

With @SenMikeLee @LindseyGrahamSC and @SenDeanHeller along with @USAmbIsrael in his new office at our new US Embassy in Jerusalem. Breathtaking. Over 70 years in the making. #History pic.twitter.com/EcIJMfmOgZ — Ted Cruz (@tedcruz) May 14, 2018

But many Arab and European leaders continue to slam Trump for upending a decades-old foreign policy in which U.S. presidents declined to weigh in on the contested city, leaving the issue to be resolved in peace talks between Palestinians and Israelis.

The Palestinians, who seek east Jerusalem as their capital, have cut off ties with the Trump administration and say the U.S. is unfit to serve as a mediator. Israel captured east Jerusalem in the 1967 Mideast war and annexed the area in a move that is not internationally recognized.

The world's largest body of Muslim-majority nations, the Organization of Islamic Cooperation, said it considers the embassy move to Jerusalem an "illegal decision" and "an attack" on the Palestinian people.

Palestinian President Mahmoud Abbas slammed the new embassy as a "U.S. settlement outpost in Jerusalem."

Violent clashes

Appearing in a video address, Trump said the U.S. is still "fully committed" to a peace deal, but that remained out of reach on Monday as protests of the opening sparked deadly clashes. At least 55 Palestinians were killed by Israeli forces and more than 1,200 wounded during violence along the Gaza border.

It was by far the deadliest day of cross-border violence since a devastating 2014 war between Israel and Gaza's Hamas rulers.

“The violence we’ve seen in response to what happened today is sad," Cruz told Fox News, saying the embassy relocation "is simply recognizing an undeniable truth [that] Jerusalem is the undivided and eternal capital of Israel."

Let's tell the truth: #Jerusalem is the eternal capital of #Israel & our embassy should be located there. https://t.co/rXvWozNcvj — Senator Ted Cruz (@SenTedCruz) December 1, 2016

Kushner, whom Trump tapped to represent the U.S. in Mideast talks but was not expected to meet with Palestinian leaders during the trip, dismissed the protests and "those provoking violence" as "part of the problem and not part of the solution."

And he told attendees that "while presidents before him have backed down from their pledge to move the American embassy once they were in office, this president delivered."

As the death toll climbed Monday, Trump took to Twitter urging people to watch the embassy opening on television and declaring it "A great day for Israel!"

Likewise, in a Fox News interview in Jerusalem, Treasury Secretary Steven Mnuchin did not mention the violence. Instead, he repeatedly referenced Jerusalem as the capital of Israel and said Trump should be praised for "taking action" to keep Americans and people in the Middle East safe.

Texas ties

Back in Texas, Gov. Greg Abbott also lauded the opening as "monumental" and "long overdue," tweeting that "it's a great day for Israel and for the U.S."

Cruz wasn't the only prominent Texan at the ceremony. Dallas megachurch pastor Robert Jeffress, a staunch Trump supporter, gave the opening prayer.

Former GOP presidential candidate Mitt Romney -- who is now running for a U.S. Senate seat representing Utah -- condemned his participation, decrying him as a bigot for prior comments in which Jeffress denigrated other faiths.

1 / 3TOPSHOT - Arab demonstrators protest in front the new United States embassy in Jerusalem on May 14, 2018. The banner reads in Arabic " Jerusalem is Arab, Palestinian, Moslem, Christian". The United States moved its embassy in Israel to Jerusalem after months of global outcry, Palestinian anger and exuberant praise from Israelis over President Donald Trump's decision tossing aside decades of precedent. / AFP PHOTO / AHMAD GHARABLIAHMAD GHARABLI/AFP/Getty Images(AHMAD GHARABLI / Getty Images) 2 / 3TOPSHOT - Palestinian mourners gather around the body of a man who was killed during a protest at the Israel-Gaza border on May 14, 2018, during his funeral at a mosque in Khan Yunis in the southern Gaza Strip. Palestinians followed through with their vow to protest massively along the Gaza border with tens of thousands demonstrating and 52 killed by Israeli fire as clashes erupted over the controversial inauguration of the US embassy in Jerusalem. / AFP PHOTO / SAID KHATIBSAID KHATIB/AFP/Getty Images(SAID KHATIB / Getty Images) 3 / 3Israeli border police officer pulls a sign from a Palestinian protestor outside the new U.S. Embassy in Jerusalem Monday May 14, 2018. Israeli soldiers shot and killed dozens Palestinians during mass protests along the Gaza border on Monday. It was the deadliest day there since a devastating 2014 cross-border war and cast a shadow over Israel's festive inauguration of the new U.S. Embassy in contested Jerusalem. (AP Photo/Eyal Warshavsky)(Eyal Warshavsky / AP)

"Robert Jeffress says 'you can't be saved by being a Jew,' and 'Mormonism is a heresy from the pit of hell,'" Romney, a Mormon, said. "He's said the same about Islam. Such a religious bigot should not be giving the prayer that opens the United States Embassy in Jerusalem."

Tension with Iran

The embassy's opening also comes days after Trump announced plans to withdraw from the Iran nuclear deal, further aligning the U.S. with Israeli Prime Minister Benjamin Netanyahu, who has alleged that Iran has violated the nuclear treaty.

The Texan has praised Trump's withdrawal from the Obama-era nuclear deal, though Democrats and global leaders warn the action could have severe international repercussions.

Cruz's Senate challenger, El Paso Rep. Beto O'Rourke, has said the deal is imperfect but that the U.S. "should not be giving up on diplomacy."

Iran’s Military Budget is up more than 40% since the Obama negotiated Nuclear Deal was reached...just another indicator that it was all a big lie. But not anymore! — Donald J. Trump (@realDonaldTrump) May 12, 2018

While in Israel, Cruz and the other lawmakers were expected to meet with senior Israeli government officials to discuss counterterrorism and national security issues, according to Cruz’s office.

The Associated Press contributed to this report.