In a meeting this morning on Capitol Hill, House Majority Leader Steny Hoyer announced that the House will vote on "a resolution opposing hate." The exact timing of that vote was unclear Thursday morning, and the text of the resolution has not yet been made public.
"What I fear is going on in the House now is an effort to target Congresswoman Omar as a way of stifling that debate. That's wrong," Sanders added.
California Sen. Kamala Harris said Thursday that she shares the concerns of the Congressional Black Caucus (CBC) that the "spotlight being put on Congresswoman Omar may put her at risk."
"You can both support Israel and be loyal to our country. I also believe there is a difference between criticism of policy or political leaders, and anti-Semitism," Harris said in a statement provided to ABC News.
Sen. Elizabeth Warren released a statement Wednesday evening also raising concerns about what she said was the "chilling effect" that equating criticism of Israel with anti-Semitism has on public debate over American foreign policy.
"Branding criticism of Israel as automatically anti-Semitic has a chilling effect on our public discourse and makes it harder to achieve a peaceful solution between Israelis and Palestinians," Warren said.
New York Sen. Kirsten Gillibrand issued a statement Thursday saying that Omar should be able to critique Israel "without employing anti-Semitic tropes about money or influence," just as "those critical of Congresswoman Omar should not be using Islamophobic language and imagery that incites violence, such as what we saw in West Virginia," referencing a poster put up outside the state House of Delegates falsely connecting Omar to the September 11th, 2001 terrorist attacks.
The West Virginia Republican Party later condemned the poster, telling the Associated Press, "Our party supports freedom of speech, but we do not endorse speech that advances intolerant and hateful views."
Asked Thursday if Omar should apologize, House Speaker Nancy Pelosi says she doesn't think the congresswoman's comment had "any anti-Semitic attitude," but added, "I understand how advocates come in with their enthusiasms, but when you cross that threshold into Congress, your words weigh much more."
The caution urged by the trio of Democratic presidential hopefuls could mark a shift in the way the debate over America's policy towards Israel, especially as the early stages of the 2020 race give way to the drumbeat of constant campaigning.
"I think now that you have presidential candidates, even if you have one presidential candidate taking this issue up, I think it will put pressure on the others to follow suit because that's where the base is," Shibley Telhami, a professor at the University of Maryland and a fellow at the Brookings Institution, told ABC News in a phone interview Thursday.
"That's why I think the traditional leadership in the House is really struggling where it never used to," Shibley, who has polled on American attitudes toward the conflict for over a quarter century, added. "It used to be, when this issue came up, it wasn't a priority for anyone, they weren't punished by their electorate. Fundraising-wise more people were in the mainstream than on the left of this issue and so that's where the pressure came from."
Public opinion polling shows that sentiments have indeed shifted, especially among Democrats. According to a Pew Research poll conducted last year, Democratic voters sympathize about equally with the Israelis as the Palestinians, with sympathy for Israel dropping 16 percentage points in the last two years.
The statements from Sanders, Harris and Warren come as the party continues to grapple with the best way to deal with the controversy surrounding Omar, a freshman Minnesota lawmaker who last year became one of the first Muslim women ever elected to Congress.
The latest saga began earlier this week when Omar made comments at a progressive event in Washington, D.C. where she again expressed frustration about the debate over America's support for the Israeli government.
"For me, I want to talk about the political influence in this country that says it is ok for people to push for allegiance to a foreign country," Omar said. "I want to ask, why is it ok for me to talk about the influence of the NRA, of fossil fuel industries, or Big Pharma, and not talk about a powerful lobby that is influencing policy?"
The comments sparked concern among Jewish groups and various Jewish members of Congress that Omar was perpetuating an anti-Semetic stereotype that accuses Jews of putting their allegiance to Israel above their loyalty to the United States.
That concern led House Democrats to begin drafting a resolution condemning anti-Semitism, a move supported by members like Rep. Debbie Wasserman Shultz, the first Jewish member of Congress from Florida.
"Because you have some members who either repeatedly or individually continued to use anti-Semitic tropes – and I’ll give them the benefit of the doubt and say it’s unknowing – then apparently we do need to put a resolution on the floor that educates people about how harmful and hurtful anti-Semitism is," Wasserman Shultz told ABC News on Wendesday.
The Minnesota congresswoman also found herself in hot water last month when she implied that congressional inaction on Israel was due in part to the monetary influence that outside lobbying groups like the American Israel Public Affairs Committee (AIPAC) have over American politicians.
Omar later apologized "unequivocally," for her comments, but has consistently defended herself against claims that she is trafficking in anti-Semetic rhetoric.
"I am told everyday that I am anti-American if I am not pro-Israel. I find that to be problematic and I am not alone. I just happen to be willing to speak up on it and open myself to attacks," Omar tweeted last week.
ABC News' John Parkinson and Roey Hadar contributed to this report.