A group of progressive US senators is pushing fellow Democrats to delay advancing major defense spending legislation, seeking to force a floor debate on pending provisions designed to expand military and intelligence cooperation with Israel, Reuters reported on Thursday.

The initiative - spearheaded by Democratic Senator Chris Van Hollen of Maryland - urges colleagues to withhold procedural votes on the National Defense Authorization Act (NDAA) until lawmakers can address proposed measures aimed at deepening security ties between Washington and Prime Minister Benjamin Netanyahu’s government.

The maneuver underscores a deepening rift within the Democratic party over traditional US policy toward Israel. As November's midterm elections draw closer, a growing number of Democratic lawmakers are openly challenging long-standing, bipartisan support for the alliance.

"As Senate Democrats, we should not be providing votes compelling him (President Donald Trump) to deepen the U.S. relationship with Netanyahu's extremist government," the lawmakers stated in a "Dear Colleague" letter obtained by Reuters.

The effort received backing from Democratic Senators Jeff Merkley of Oregon, Ed Markey and Elizabeth Warren of Massachusetts, and Peter Welch of Vermont. Senator Bernie Sanders of Vermont, an independent who caucuses with Senate Democrats and has been one of the most vocal critics of Israel, also signed the letter.

Van Hollen has also emerged as one of the Capitol's most prominent critics of US policy toward Israel, frequently pushing to enforce the Leahy Law to restrict arms transfers over human rights concerns and accusing the Netanyahu government of restricting humanitarian aid to Gaza.

Congress is currently hammering out the final details of this year's NDAA, which sets policy and authorizes funding for much of President Donald Trump's proposed $1.5 trillion military budget. Versions of the legislation passed by committees in both the House and Senate contain provisions to expand US-Israel defense cooperation, as is the case every year.

The letter also noted that draft versions of the fiscal 2027 Intelligence Authorization Act - a measure routinely attached to the broader defense authorization package - include provisions to tighten bilateral intelligence sharing with Israel.