A bipartisan slate of 27 U.S. senators signed on to a letter to Secretary of State Hillary Rodham Clinton to press the Palestinian Authority to address incitement.

The letter, sent Tuesday but initiated two weeks ago by Sens. Kirsten Gillibrand (D-N.Y.) and Mark Kirk (R-Ill.), focuses on the March 11 massacre of five members of a Jewish family in Itamar, a settlement in the northern West Bank, and suggests that the Palestinian Authority, under the leadership of Mahmoud Abbas, has not done enough to stem incitement.

"Although President Abbas has expressed his sorrow over the Itamar massacre, the Palestinian Authority must take unequivocal steps to condemn the incident and stop allowing the incitement that leads to such crimes," the letter said. "Educating people toward peace is critical to establishing the conditions to a secure and lasting peace."

A similar letter to President Obama, initiated by U.S. Reps. Steve Austria (R-Ohio) and Steve Rothman (D-N.J.), was launched at about the same time and is still garnering signatures in the House of Representatives.

Dovish Jewish groups such as J Street and Americans for Peace Now oppose the letters, saying they lack balance by not noting Israeli incitement and steps the Palestinian Authority has taken to tamp down incitement.