On Thursday, a group of Democratic senators released a letter they have been working on for weeks, warning Israeli leaders against unilaterally annexing portions of the West Bank.

The letter, signed by 19 Democratic senators and authored by Sens. Chris Murphy (D-CT), Chris Van Hollen (D-MD) and Tim Kaine (D-VA), is a watered-down version of the letter the trio drafted and distributed to fellow senators earlier this month. The initial draft threatened that unilateral annexation would end bipartisan congressional support for Israel.

The first draft of the letter had garnered seven signatures in addition to Van Hollen, Murphy and Kaine: Sens. Dick Durbin (D-IL), Tammy Baldwin (D-WI), Brian Schatz (D-HI), Patrick Leahy (D-VT), Sherrod Brown (D-OH), Tom Udall (D-NM) and Jeff Merkley (D-OR).

A second draft of the letter, which softened the original language, was circulated among Senate offices and gained additional signatories. 

The letter released on Thursday appears to have been further revised. The second draft of the letter suggested that annexation would “undermine” the close relationship between the two nations. The final letter added that “unilateral annexation puts both Israel’s security and democracy at risk.”

The last paragraph of the finalized letter, which was addressed to Prime Minister Benjamin Netanyahu and Defense Minister Benny Gantz, includes a warning that “If you move forward with unilateral annexation, we would not support that action.” Both prior versions of the letter read “If you move forward with unilateral annexation, we could not support that action.”

The final letter’s signatories, in addition to the original 10, include Ed Markey (D-MA), Martin Heinrich (D-NM), Sheldon Whitehouse (D-RI), Jeanne Shaheen (D-NH), Tammy Duckworth (D-IL), Tom Carper (D-DE), Patty Murray (D-WA), Elizabeth Warren (D-MA), and Bernie Sanders (I-VT).

Sen. Ben Cardin (D-MD), who did not sign on to the letter, told Jewish Insider earlier this month: “I don’t think it is helpful for us to sow dissension in the United States as it relates to the support for Israel.”

Sen. Dianne Feinstein (D-CA) issued her own letter to Israeli Prime Minister Benjamin Netanyahu, the text of which was released last week.

The letters had the backing of J Street, which sent action alerts to its members urging them to lobby their senators to sign onto the letter.

Read the full text below with the updated language from the prior draft.

Dear Prime Minister Netanyahu and Defense Minister Gantz Deputy Prime Minister Speaker Gantz,

As American lawmakers who have long supported strong U.S.-Israel ties and a just resolution to the Israeli-Palestinian conflict, we write to express our grave concern with provisions in the recently concluded government agreement to consider unilateral annexation of Palestinian territory as early as this July. Such an action would mark a dramatic reversal of decades of shared understandings between the United States, Israel, the Palestinian Authority Palestinians and the international community, and would have a clear impact on severe ramifications for both Israel’s future and our vital bilateral and bipartisan relationship.

A deep commitment to Israel’s security and a shared set of democratic values are foundational elements of the close relationship between our countries. We are therefore concerned that a unilateral annexation puts both Israel’s security and democracy at risk.– and annexation would threaten undermine both. Annexation would betray our shared democratic values by denying Palestinians’ right to self-determination in a viable, sovereign, independent and contiguous state. It could would likely bring an end to Palestinian security cooperation with Israel, directly threatening the security of the Israeli people, and would endanger Israel’s crucial peace agreement with Jordan.

On the world stage, unilateral annexation will be met with deep concern from our mutual allies and partners, including Jordan and Egypt, and nearly universally viewed as a violation of international law. The formalization of a fragmented and disconnected array of Palestinian islets surrounded by Israeli territory would be rejected by the international community as both unequal and undemocratic. And most concerning, a unilateral annexation outside of a negotiated agreement would likely erode the strong support among the American people for the unwavering security assistance special relationship and diplomatic partnership from with the United States that Israel currently enjoys.

We hope you view this relationship as the strategic asset it is for both of our countries. As friends and supporters of Israel, we caution you against taking unilateral steps that would fray our unique bonds, imperil Israel’s future and place out of reach the prospect of a lasting peace. If you move forward with unilateral annexation, we would could not support that action and would sadly conclude that Israel no longer values the bipartisan support that Congress has provided it for decades. This is consistent with long-standing American policy opposing unilateral actions by either party to the conflict. Pursuit of a viable, negotiated two state solution is essential to ensuring our shared democratic values and lasting bipartisan support for Israel in Congress.