Israel’s prime minister Wednesday gave a cool reception to a renewed peace offer from the Arab world, in a fresh sign of trouble for U.S. efforts to restart Mideast peace talks.

With Secretary of State John Kerry expected to return to the region next week as part of his mission to resume Israeli-Palestinian negotiations, neither side seems to be yielding ground. Kerry has indicated that his patience is wearing thin and that he may turn his focus elsewhere if his efforts do not yield results.

Kerry had trumpeted the Arab peace initiative as a significant achievement when he persuaded the Arab League to relaunch it in late April, with slight changes meant to entice Israel.

But during a parliamentary debate on the peace plan Wednesday, Netanyahu made scant mention of the plan and gave no indication that he was willing to embrace it.

“We are willing to discuss initiatives that are offers, not dictates,” he said. “We are in favor of negotiating without preconditions immediately.”

When it was first issued in 2002, the Arab initiative was a breakthrough, ending decades of official refusal to recognize Israel’s right to exist.

The initiative, endorsed by the Arab League and the 57-member Organization of Islamic Cooperation, offered Israel normalized relations in exchange for a full withdrawal from territories captured in 1967 to make way for a Palestinian state. However, it was overshadowed by Israeli-Palestinian fighting and was greeted with skepticism by Israel.

In a significant step, Kerry persuaded the Arab League in April not only to renew its peace initiative, but to sweeten it by saying the final borders between Israel and a future Palestine could be modified from the 1967 lines through agreed land swaps. This small but significant amendment could open the way for Israel to keep some West Bank settlements as well as holy sites in east Jerusalem.

The twin issues of settlements and the 1967 lines have been at the heart of a nearly five-year breakdown in peace efforts. The Palestinians claim the West Bank, east Jerusalem and the Gaza Strip, all captured by Israel in the 1967 Mideast war, for their future state.

The Palestinians object to Israeli settlement construction in the West Bank and east Jerusalem and demand that Israel accept the 1967 lines as the baseline for border negotiations. Offers based on the pre-1967 lines by two previous Israeli governments failed to result in a peace accord.

Although the Palestinian positions have been accepted by the international community, Netanyahu refuses to stop building in settlements or commit to the 1967 lines, saying all disputes should be settled in negotiations.

If peace efforts fail, the Palestinians say they will resume a campaign of joining U.N. and other international bodies in order to press war crimes charges against Israel.

Kerry has implored both sides to show flexibility as he tries to restart negotiations. He has urged Israel to curtail its settlement construction as much as possible, while calling on the Palestinians to suspend their efforts for international recognition. He has also claimed that he is organizing billions of dollars of investment projects in the Palestinian economy.

For now, however, Kerry appears to be making little headway, and in a speech this week, Kerry warned that time was running low.

Speaking to reporters in Washington on Wednesday, State Department spokeswoman Jen Psaki said that now was the time for the sides to make “tough choices” and signaled that Kerry might not make the trip if he didn’t see signs of progress.

“I think he will go back if he feels there is an opportunity to move things forward,” she said. She declined to set any deadlines for progress.