Democratic progressives are attempting to reset the traditional bipartisan U.S. support for Israel, though real policy changes will have to wait for future U.S. elections in 2022 and 2024 that could produce enough progressive seats to force deeper changes to U.S.-Israeli relations. House Democrats stripped a $1 billion provision to resupply Israel's Iron Dome from the U.S. government's funding package Sept. 21 after progressive Democrats opposed to the provision threatened to withhold votes for it. This was the second time the same group of Democrats has attempted to block U.S. aid to Israel: In May during the Gaza War, the same caucus attempted to block a $735 million sale of U.S. precision-guided weapons to Israel, though the deal ultimately went through. And while Israel downplayed the move and Democratic House Majority Leader Steny Hoyer said that he would bring the funding forward in a separate bill, the move still marked a break in U.S. political tradition and signaled progressives' willingness to block even sales of defensive weapons system to Israel. 

• The funding bill passed 220-211 with no Republican support. This slim margin allowed progressives (the caucus has 95 members) a unique opportunity to use their numbers to force the provision out of the bill. 
• Israel's Iron Dome was depleted during the recent Gaza war, when it shot down thousands of projectiles fired by militants. Traditionally, the United States provides funds to rearm Israeli forces after major confrontations with regional rivals, including after the 2014 and 2009 Gaza wars and the 2006 Hezbollah War. 

While Iron Dome is likely to be funded through other legislation, demographic and political changes in the United States will continue to strengthen the progressive faction in the Democratic Party, which is likely to continue attempting to block further aid to Israel. With Congress narrowly split, future pro-Israel legislation could become contested by these same progressives, especially if Republicans do not join in voting with the Democrats in voting for legislation that might include Israeli aid. Their influence on committees might also slow the legislative process for the approval of arms deals or resupply deals for Israel. If Republicans join with more centrist Democrats to vote for Israeli aid, however, progressives will be unable to block it. They also have less influence in the Senate, where more centrist Republicans are willing to break party lines to vote with Democrats and thus offset progressive votes. 

• U.S. support for Israel used to be strongly bipartisan, but U.S. public opinion has been changing, driven by new political opinions developing in youth voters, Jewish voters and partisan Democrats. These voters helped seat the progressive group of Democrats who have questioned U.S.-Israeli ties and demanded changes to Israeli policy toward the Palestinians. 

Future elections in 2022 and 2024 could strengthen this faction of the Democrats if they take more congressional seats through primaries and races and/or reshape the national narrative around Israel to incentivize sitting Democrats to shift their position on Israeli aid. It is unclear how the midterm elections and national election in 2024 will pan out, but if they play out favorably for the progressives, they might upend traditional U.S. support for Israel. Another major Palestinian-Israeli conflict also would likely further erode U.S. public support for Israel, giving room to politicians even closer to the center to question U.S. relations with Israel.