Washington (CNN) First, President Donald Trump accused Democrats of becoming an "anti-Jewish" party . Then, he repeated his claims. And on Monday, Vice President Mike Pence picked up the mantle, accusing the Democratic Party of having been "co-opted" by anti-Semites.

"It's astonishing to think that the party of Harry Truman, which did so much to create the state of Israel, has been co-opted by people who promote rank anti-Semitic rhetoric and work to undermine the broad American consensus of support for Israel," Pence said on Monday, speaking at the American-Israel Public Affairs Committee's annual conference in Washington.

Pence's comments amounted to the latest effort by Republicans to cast Democrats as anti-Semitic and anti-Israel after freshman Democratic Rep. Ilhan Omar of Minnesota made a series of comments in the past several weeks that played up longstanding anti-Semitic stereotypes. Her comments were widely condemned, including by members of Democratic Party leadership. The AIPAC conference is proving fertile ground for the President and his allies to once again call attention to the issue, and reap the political benefits of positioning Republicans as the more pro-Israel party.

Senate Minority Leader Chuck Schumer, also speaking at AIPAC, hit back at Trump's claims -- although he did not mention the President by name.

"Those who seek to use Israel as a means to scoring political points do a disservice to both Israel and the United States," the New York Democrat said.

He said it is "demonstrably false to say Democrats are anti-Israel" and that it "hurts the Israel-US relationship."

Even though Jewish voters overwhelmingly support Democrats and most Jewish members of Congress are Democrats, the President and his allies have continued to press their case, suggesting rampant anti-Semitism in Democratic ranks -- even as they tie their claims back to a single member of Congress.

But the broad anti-Semitism allegations against Democrats, while unfounded, are giving Republicans an opportunity to call attention to the widening divide in the Democratic Party over US policy toward Israel. While most Democrats continue to embrace unequivocally pro-Israel positions, an increasing number of progressive Democrats are questioning the status quo and at a minimum, voicing increasingly strong criticisms of the policies of the current right-wing Israeli government. The Democratic National Committee did not immediately respond to CNN's request for comment.

Despite the fact that the President did not address the AIPAC conference this year, Pence called attention to the absence of most major Democratic presidential candidates at the conference this year -- even accusing "eight Democratic candidates for president" of "boycotting."

"Anyone who aspires to the highest office in the land should not be afraid to stand with the strongest supporters of Israel in America. It is wrong to boycott Israel and it is wrong to boycott AIPAC," Pence said, drawing raucous applause at the pro-Israel conference.

While the progressive group MoveOn called on Democratic candidates to boycott the conference and several are not attending this year, the absences in most cases were not intended to make a statement, according to campaign sources. While it would be unusual for presidential candidates to avoid the AIPAC conference during an election year, it's not standard practice for them to attend in the year ahead of the election. Trump, for example, attended the AIPAC conference in 2016, but not in 2015. Top Democrats attending this year include House Speaker Nancy Pelosi and Schumer.

Their absence nonetheless set up a contrast that Trump and his allies are sure to continue to call attention to, as they coincided with Trump's signing of a proclamation recognizing Israel's sovereignty over the Golan Heights alongside Israeli Prime Minister Benjamin Netanyahu

While US politicians -- Democratic and Republican -- wrestle with criticism of Israel in their ranks and how to pursue a pro-Israel policy that does not ignore alleged Israeli violations of international law -- as with settlements, for example -- Trump has pursued a policy that is in lockstep with Israel, going beyond even positions held by his Republican predecessors by overturning decades of US policy in recognizing Jerusalem as the capital of Israel and Israeli sovereignty over the Golan Heights.

The territory was seized by Israel during the Six Day War in 1967 with Syria. It is still considered to be occupied territory by the international community.

Trump has talked about generating a "Jexodus" of Jews moving out of the Democratic Party and joining Republican ranks and while there is no evidence that is occurring, the President is in the meantime solidifying his support among evangelical Republicans who are a key component of his political base.

The President has flung broad allegations of anti-Semitism at Democrats even as he has faced criticism for repeatedly failing to condemn white supremacists, including those touting anti-Semitic views. Most notably, Trump suggested that there were "very fine people" on both sides of protests in Charlottesville, Virginia, last year, where neo-Nazis chanted "Jews will not replace us." And the President has not directly condemned the white supremacist comments made by Republican Rep. Steve King of Iowa.

Trump also took heat for trafficking in anti-Semitic stereotypes and imagery after he tweeted a picture of Hillary Clinton surrounded by piles of cash and a Star of David that included the words "most corrupt candidate ever!"

He also retweeted several tweets from neo-Nazi accounts and initially refused to disavow support from the white supremacist David Duke.

Schumer, at AIPAC, stressed the need to call out anti-Semitism in the political realm --- appearing to reference Omar, though he did not use her name, and referencing Trump's comments after Charlottesville.

"When someone names only prominent Jews as trying to 'buy' or 'steal' our elections, we must call it out. When someone says that being Jewish and supporting Israel means you're not loyal to America, we must call it out. When someone looks at a neo-Nazi rally and sees some 'very fine people' among its company, we must call it out. When someone suggests money drives support for Israel, we must call it out," he said.