Sen. John Curtis (R-UT) announced Thursday that he will not support Jeremy Carl, President Donald Trump’s nominee for assistant secretary of state for international organizations, a move that could effectively sink the nomination in committee.

Curtis cited what he described as “anti-Israel views and insensitive remarks about the Jewish people” as grounds for his opposition, stating he did not believe Carl was the right choice to represent the United States in international forums. His defection is significant: if all Democrats vote against Carl, as expected, the nominee would lack the votes necessary to advance out of the Senate Foreign Relations Committee.

Democrats, including Senate Minority Leader Chuck Schumer and Sen. Chris Murphy (D-CT), have already signaled strong opposition. Murphy labeled Carl a “white nationalist” and criticized past comments related to immigration and cultural identity. During the hearing, Democrats pressed Carl over prior remarks referencing “anti-White discrimination,” “white culture,” and concerns about mass immigration. Carl responded that he believes unity around a common American culture strengthens the country and weakens division.

Other Democrats questioned Carl over statements about Jewish history and the Holocaust. Carl acknowledged that some past comments were poorly phrased and said he regretted minimizing the impact of the Holocaust. He emphasized that he understands the need for restraint during the confirmation process while balancing his current policy work.

If confirmed, Carl would oversee U.S. engagement at the United Nations and other multilateral institutions, a role central to advancing the administration’s foreign policy priorities. He previously served in the Interior Department during Trump’s first term and is currently affiliated with the Claremont Institute.

Curtis’s decision has drawn criticism from conservatives who argue that, at a time when the administration is working to reshape U.S. engagement in international organizations, Republican unity is critical. With Democrats unified in opposition, even a single GOP defection carries significant consequences for Jeremy Carl.