U.S. Sen. Edward Markey is facing pressure from the coalition of progressive organizations, staff and youth volunteers that became central to his 2020 reelection campaign to take a harder stand against Israel for the role the U.S. ally has played in the escalating violence and civil unrest between Israel and Palestine.

The death toll this week has continued to rise as rockets and missiles launched by Israel and Hamas into Israeli cities and Palestinian territories in Gaza have killed dozens of people, including children.

Markey on Tuesday called for an end to the violence, which has been centered around Israel's policy of resettling Palestinians, but his statement is being criticized by some in the "Markeyverse" who are sympathetic to the Palestinian cause for taking too much of a "both sides" position on the conflict.

"Senator Markey told us that young people would lead the way, and now it is time for him to listen to us and stand up for Palestinian lives," said former campaign fellow and Students for Markey organizer Cherilyn Strader.

Strader was one of more than 500 individuals and groups, including former staff, volunteers, donors and endorsing organizations, to sign a statement describing themselves as "upset and disappointed" with Markey's position on the conflict.

Other groups and people involved include the Sunrise Movement, Massachusetts Peace Action, IfNotNow Boston, Jewish Voice for Peace Boston, state Rep. Erika Uyterhoeven and Cambridge City Councilor Jivan Sobrinho-Wheeler.

Markey on Tuesday said that Palestinians and Israelis "deserve peace and safety."

"The violence must stop and all sides must protect innocent civilians. The Biden Administration should continue being fully engaged to help de-escalate this moment," the Malden Democrat wrote on Twitter.

In a series of tweets, he also said Israeli plans to force Palestinians from their homes and the raid on the Al-Aqsa mosque in Jerusalem, which is sacred to both Muslims and Jews, have "contributed to a spiral of violence that must be de-escalated before more innocent people are hurt and killed."

In his final tweet, Markey wrote: "Israel has the right to defend itself from indiscriminate rocket attacks and no one should fear being forcefully evicted from their homes. We need peace."

Those upset with Markey say he is ignoring the voices of the young, progressive activists that helped get him reelected in his campaign against former U.S. Rep. Joseph Kennedy III.

"He followed in the footsteps of Mitt Romney and Donald Trump by saying it's a 'both sides' issue, which ignores the current and historical power imbalance between Israel and Palestine and couldn't be farther from the truth," the protest statement read. "Senator Markey's refusal to support justice in Palestine is antithetical to the Green New Deal and the progressive movement that won him re-election."

The group is asking Markey to demand an investigation into the role U.S. arms and funding of Israel has played in the displacement of Palestinians. They also called for the application of U.S. Arms export regulations to prevent their deployment against civilians in Gaza and for Markey to introduce legislation in the Senate, similar to a bill filed by Minnesota Rep. Betty McCollum, promoting human rights and the safety of Palestinian children.

Markey's office said the senator "welcomes debate on all issues," and repeated his position that there needs to be "an immediate ceasefire."

"Transparency and accountability are core values for Senator Markey, and he stands by the commitment he made to this powerful movement of young people. We may not always agree, but it's important to uphold that commitment, to listen, to value and respect others," Markey spokesman Geoff Burgan said in a statement.

"Senator Markey will continue to call for peace and for an end to the violence against innocent Palestinian and Israeli children and families. The United States must be fully engaged to help de-escalate the violence. We need an immediate ceasefire," Burgan said.

Markey is not alone in facing criticism from the left wing of his party over his position on the Israeli-Palestinian conflict. President Joe Biden has taken heat from progressive leaders like U.S. Rep. Alexandria Ocasio-Cortez, who was Markey's partner on the Green New Deal. Ocasio-Cortez said the president was "taking the side of the occupation" after he spoke this week with Israeli Prime Minister Benjamin Netanyahu and said Israel has a right to defend itself.

In the Massachusetts delegation, U.S. Rep. Seth Moulton on Wednesday said he remains a "fried of Israel," but said it was time to tell a friend "hard truths."

"The hard truth is this: the decision to relocate Palestinian families for settlements is morally wrong. The policy of settlements is designed to take territory that the world -- including Israel -- has agreed belongs to Palestinians. It is a home-by-home invasion, spread over years. I deeply oppose it, and anyone who wants to see peace in the region should as well," Moulton said in a statement.

Moulton also said Israel and Israelis "provoked violence" by sending Israeli police into Al-Aqsa and organizing marches in East Jerusalem during Ramadan. The Salem Democrat said he supports a two-state solution that recognizes East Jerusalem as the capital of a Palestinian nation.