JERUSALEM — U.S. Secretary of State John Kerry’s closed-door diplomacy to broker peace between Israel and the Palestinians has burst into a public spat, with both sides trading blistering criticisms, Republican senators showing up in Jerusalem to argue Israel’s side, and Palestinian demonstrators protesting his visit.

Kerry is on his 10th visit to the region to try to craft a peace treaty that would create a Palestinian state alongside Israel.

He met for three hours on Friday with Israeli Prime Minister Benjamin Netanyahu. Later in the day, Kerry traveled to Ramallah, West Bank, to speak with Palestinian President Mahmoud Abbas. Although battered by sniping from all sides, Kerry remained upbeat – at least publicly.

Asked if he was making progress, Kerry replied that progress is being made every day.

Earlier, about 150 Palestinians demonstrators marched through the streets of downtown Ramallah to protest Kerry’s visit.

So far, the two sides have engaged in about 20 rounds of negotiations, which have entered a more intense phase. Kerry is asking both leaders to start making tough, highly political decisions in hopes of narrowing differences and agree on a framework that will outline a final peace pact.

The goal is for the framework, or series of guidelines, to address all core issues, including borders between Israel and a future Palestinian state, Palestinian refugees and conflicting claims to the holy city of Jerusalem. No agreement on a framework is likely during Kerry’s visit.

Political activist Abdallah Maslamani said a proposed framework that would guide negotiations on a deal protect the security interests of “the terror state of occupation,” a reference to Israel.

One night earlier, the digs were coming from the other side. Netanyahu lashed out at Abbas, accusing him of embracing terrorists “as heroes.”’

Netanyahu criticized Abbas’ homecoming for more than two dozen Palestinians released earlier this week from Israeli jails where they had served time for deadly attacks against Israelis. The Palestinian leader never condoned their crimes, but Netanyahu took offense.

“To glorify the murders of innocent women and men as heroes is an outrage,” Netanyahu said, dampening hope that much progress would be made on the contours of an eventual peace accord during Kerry’s visit.

Even in Jerusalem, Kerry couldn’t escape domestic politics interfering with international diplomacy. Three Republican senators held a news conference after meeting with the Israeli leader, reiterated his concerns, thereby emboldening Netanyahu’s position right before Kerry’s delicate talks with Abbas.