With multiple vulnerable Democratic senators up for re-election next year, the opportunity to put a feather in their cap has presented itself as the Republican-controlled House pushes President Biden to freeze $6 billion destined for Tehran. Multiple Democrats have already said they would support such a proposal. 

On Thursday, the House passed the No Funds for Iranian Terrorism Act, which would direct Mr. Biden to sanction a bank in Qatar that is currently acting as a middle-man, holding the $6 billion that America helped move from a South Korean firm to the Gulf. The money, proceeds from Iran’s sale of oil, was moved out of South Korea following the release of American hostages from Iran in August. 

The bill passed the House by a margin of 307-119. 

The Biden administration has so far pushed back against calls for those funds to be frozen in the wake of Hamas’s October 7 attack on Israel, leading the chairman of the Foreign Affairs Committee, Congressman Michael McCaul, to introduce the legislation. 

“No matter what assurances the Biden administration makes, the president of Iran has said he would use this money however he wants,” Mr. McCaul said in a statement. “Iran is the largest state sponsor of terror in the world. We cannot give them another $6 billion for their terror operations, which include ongoing support for Hamas’ unprovoked war against our ally Israel.”

Halting the $6 billion transfer became a priority for Israel’s staunchest congressional allies following the October 7 attack. A former speaker, Congressman Kevin McCarthy, said at a press conference just 48 hours after the attack began that the funds should not be moved and that his colleagues would attempt to halt the transaction. 

Multiple Democratic members of the Senate — many of whom will face tough re-election bids less than 12 months from now — have said in recent weeks that they would support such an idea. 

“As American intelligence officials continue to investigate the terrorist attacks carried out by Hamas, we should review our options to hold Iran accountable for any support they may have provided,” Senator Tester, the Montana Democrat who faced more than $20 million in negative advertising during his last race in 2018, said. “At a minimum, we should immediately freeze the $6 billion in Iranian assets and explore other financial tools we have at our disposal.”

Senator Manchin, who has since announced his retirement, joined Mr. Tester in calling on the Biden administration to freeze the money. 

A Pennsylvania scion, Senator Casey, also called for a temporary stop in the transfer until American intelligence can determine Iran’s exact level of involvement in the attack. The funds “should remain frozen until we can determine whether Iran played a role in the attack and what the appropriate U.S. response should be.” He also noted that “none of the sanctioned funds have been transferred to Iran.”

Mr. Biden has not yet said anything about the legislation that now sits in the Senate. A spokesman for the National Security Council did not immediately respond to a request for comment. 

Three of the upper chamber’s most vulnerable Democrats seeking re-election in 2024 — Senators Brown of Ohio, Baldwin of Wisconsin, and Rosen of Nevada — wrote to Secretary Blinken to ask that he stop the $6 billion transfer. “We therefore strongly urge you to make it official U.S. policy to freeze the $6 billion in Iranian assets currently held in Qatar, and continue to hold Iran accountable for its violent and destabilizing actions, including direct support of Hamas,” the senators wrote. 

Mr. Brown, who serves as chairman of the Banking Committee, has said he and his committee colleagues will launch an investigation into the funding sources for Hamas’s attack on Israel. 

Vulnerable Democratic senators have put the president in a bind before. In March, Messrs. Tester and Manchin joined with their Republican colleagues to pass a bill that would have gutted a Department of Labor rule recommending that pension funds invest in environmental and social governance funds, which the GOP has derided as “woke finance.”

The two Democrats’ defection to the GOP side led Mr. Biden to issue the first veto of his presidency.