Palestinian Authority President Mahmoud Abbas is in Germany to speak with German Chancellor Angela Merkel over European support for the creation of a Palestinian state. (Carsten Koall/GETTY IMAGES)

The countdown to a Palestinian bid next week for membership and recognition as a state in the United Nations brought a stark warning from Israel on Wednesday that approval would result in “harsh and grave consequences” for the Palestinians.

The threat by Foreign Minister Avigdor Lieberman was the sharpest yet in an escalating cycle of rhetoric on all sides of the conflict. While the Palestinians say they will go ahead with the move, the Obama administration dispatched two senior envoys to the region Wednesday to restate the American case against the statehood bid.

There has been no indication that the move could bring an eruption of violence, but both sides are preparing for diplomatic retaliation, which could ignite tensions and unrest.

Lieberman would not say Wednesday what specific actions Israel might take. But a senior Israeli official who briefed reporters recently on possible Israeli responses said that a “basket of tools” was being assembled in response to the statehood bid and that the moves could range from restricting travel for Palestinian leaders in the West Bank to more far-reaching steps.

For their part, Palestinian Authority officials in the West Bank have called for mass demonstrations in cities and towns in support of the initiative, and the Israeli army and police have responded by publicizing their preparations to confront possible marches toward Israeli checkpoints and settlements.

Washington’s opposition to the Palestinian statehood initiative and an expected U.S. veto of the move at the U.N. Security Council have drawn warnings from some Palestinian officials that American standing in the region could be harmed at a time of profound change.

Yasser Abed Rabbo, a senior aide to Palestinian Authority President Mahmoud Abbas, echoed the growing discontent in remarks last week on Voice of Palestine radio.

“This shows not only disdain for the Palestinian position,” Abbed Rabbo said of the U.S. stance, “but also scorn for what is happening in the Arab world: a revival seeking justice for the Arab peoples and the region as whole.”

The Palestinian Authority receives about $500 million a year in U.S. economic assistance and training aid for its security forces, but deep opposition in Congress to the statehood move could leave that funding in jeopardy.

A House appropriations subcommittee has passed a bill that could cut off aid to the Palestinian Authority over the U.N. bid, although it is still unclear whether such a measure could ultimately win Senate approval.

“If the Palestinians continue on their current path, the question before the Congress will not be what portion of our aid will be cut, but rather what portion will remain,” Rep. Steve Chabot (R-Ohio), head of the Middle East subcommittee of the House Foreign Affairs Committee, said at a hearing Wednesday on aid to the Palestinians.

While Prime Minister Benjamin Netanyahu has carefully avoided any public hint of how Israel may respond to the U.N. bid, Lieberman, the foreign minister, is among the hawkish members of his government who have urged diplomatic retaliation.

Lieberman has called the Palestinians’ move a violation of the 1993 Oslo accords between Israel and the Palestine Liberation Organization, which created the Palestinian Authority and govern its relations with Israel. The accords call for negotiations to resolve core issues in dispute and reach a permanent peace agreement.

Scrapping the Oslo accords could undermine critical areas of contact between Israel and the Palestinians, such as security cooperation, economic agreements and allocation of water resources in the West Bank. It would also mean the abandonment of a decades-old blueprint to achieve peace through an interim period of Palestinian self-rule, followed by negotiations to reach a two-state solution to the conflict.

Uzi Landau, a cabinet minister from Lieberman’s rightist Yisrael Beiteinu party, has urged the government to respond by annexing to Israel large swaths of the West Bank, including major settlements and the Jordan Valley.

In a similar vein, Palestinian officials have warned that they could use their new status at the United Nations to pursue legal action against Israel in international tribunals, including the International Criminal Court. And while the Obama administration has left no doubt about its opposition to the statehood bid, some leading Arab officials have said that the stance could cost Washington dearly in the Middle East.

The U.S. envoys who arrived in Israel on Wednesday were dispatched in what State Department officials characterized as an eleventh-hour attempt to cut a deal that might avert a showdown at the United Nations.

It was the second such trip in a week for the two envoys — chief Middle East negotiator David Hale and the National Security Council’s longtime regional adviser, Dennis Ross. The U.S. officials were to meet with Netanyahu and Defense Minister Ehud Barak late Wednesday, followed by talks Thursday with Abbas, the Palestinian leader.

U.S. officials were tight-lipped on what new initiatives, if any, the two men carried with them. Their travel coincided with similar efforts by European diplomats.

“We continue to see any kind of effort by the Palestinians in New York as counterproductive and not in the interests of achieving a two-state solution, which is our goal,” State Department spokesman Mark Toner said of the latest diplomatic mission. “We are working hard to get both parties back to the negotiating table and avert any sideshow in New York on statehood.”

Staff writers Joby Warrick and Mary Beth Sheridan in Washington contributed to this report.