Supporting Israel in an unequivocal manner has become a key issue in the campaign for the Republican presidential nomination in 2016.

“If push comes to shove, I am going to be on Israel’s side every single time,” Marco Rubio pledged on Friday.

“If I am president, America will stand unapologetically with the nation of Israel,” Ted Cruz followed suit.

The issue was brought to bear on stage by the two junior Senators vying for the Republican nomination not by attacking President Obama or questioning the Democratic candidates’ bona fides, but by taking down the Republican Party’s front-runner Donald Trump. Last Thursday, for the first time in the 2016 election cycle, Cruz and Rubio pounced on Trump for taking “an anti-Israel position” in suggesting he would take a “neutral” approach to the Israeli-Palestinian conflict.

Fending off the attacks, Trump reassured voters he’s “very pro-Israel, very pro.” On Saturday, Trump tweeted, “It was an honor to be the Grand Marshall- in the Salute to Israel Parade back in 2004,” with an attached picture of him waving to the crowd at the parade.

But as the race moves past Super Tuesday to states like Florida and Ohio (on March 15), the Rubio campaign seems eager to portray Trump as weak on Israel in an effort to mobilize Jewish Republican voters in these battleground states to join the “Never Trump” movement.

In campaign events over the weekend, Rubio hammered Trump on Israel. “When I’m president, our allies will know they are our allies,” Rubio repeated in rally after rally. “Donald Trump said he doesn’t want to take a side when it comes to the Israeli-Palestinian conflict. I will take a side. We’re going to be 100 percent on Israel’s side.” During a campaign rally in Richmond, Virginia, Rubio stressed, “The only (peace) deal I’m interested in, is one that recognizes Israel has a right to exist as a Jewish state and Jerusalem as its capital.”

On Saturday, Adam Hasner tweeted a picture of Rubio volunteers standing in Arkansas with a poster that suggests voting for Trump will come at the cost of supporting Israel. “Stop supporting Israel, vote Trump,” the poster read.

We asked Hasner, who’s the former majority leader of Florida’s House of Representatives and co-chair of the Rubio campaign in Florida, if Trump’s position on Israel will become a front-and-center issue leading up to the Florida primary – a must-win for the Florida Senator.

“It should be an issue for those who believe the safety and security of Israel is important,” Hasner told Jewish Insider. “Marco has been making the case based on Trump’s own words. Trump has said he would be neutral in dealing with Israel. Marco has said clearly and often that he will be on Israel’s side. It’s that simple.”

According to Hasner, “For a guy that never seems to have a problem taking sides, it’s a sad example of Trump displaying moral relativism between Israel and those seeking to destroy Israel.”

It remains to be seen if Rubio’s aggressive campaign will help him overcome a double-digit lead by Trump, according to recent public opinion polls. A Quinnipiac poll from last summer showed that 61 percent of Floridians oppose the Iran nuclear deal reached with Iran last summer. Rubio pledged to cancel the nuclear agreement on his first day in office.

The Emergency Committee for Israel released a 30-second TV ad on Sunday, highlighting Trump’s disturbing affection for anti-American dictators. The ad will appear online and on television in primary states this week, according to ECI’s news release. “If you’re pro-Israel, you shouldn’t be pro-Trump. Apologists for dictators aren’t reliable friends of the Jewish state,” said Bill Kristol.