Israel's defense minister accused Iran and Syria of masterminding a suicide bombing in Tel Aviv the day before that wounded 20 people and said the militant group believed responsible would be targeted in raids. A Syrian official denied involvement.

Islamic Jihad, which is backed by Syria and Iran, claimed responsibility for bombing a fast-food restaurant Thursday. The Palestinian attacker, who witnesses said posed as a peddler selling disposable razors, walked into the restaurant and blew himself up even though most customers were sitting outside at sidewalk tables, police said.

The explosion wrecked "The Mayor's Shwarma," a restaurant specializing in grilled meat sandwiches. It is located in a rundown area of downtown Tel Aviv that has been hit repeatedly by Palestinian attackers.

After a late-night meeting with security officials, Defense Minister Shaul Mofaz said: "We have definitive proof that the financing of the terror attack ... came directly from Iran, while the planning was carried out in Syria."

He said the findings would be shared with American and European officials.

Faisal Sayegh, the director of Syria's state-run broadcast media, said Syria had "nothing to do with the operation."

Mofaz said Israel would tighten security around Nablus, the West Bank city where the bomber lived, and target Islamic Jihad militants in raids, but no major reprisals were planned.

Israel accuses Iran of trying to develop nuclear weapons and has supported U.S.-backed efforts to take the matter to the U.N. Security Council.

Israel considers Iran to be its biggest threat — a concern that has grown since Iranian President Mahmoud Ahmadinejad said Israel should be "wiped off the map."

Palestinian leader Mahmoud Abbas condemned the attack and said it was an attempt to sabotage Wednesday's Palestinian vote. Islamic Jihad is not participating in the election.

The militant group Hamas staged mass rallies with tens of thousands of supporters across the Gaza Strip on Friday in a final show of strength before the vote.

At a rally in Gaza City, a Hamas leader shouted: "Are you going to vote for Hamas?" The crowd, waving green Hamas flags, responded in unison: "Yes to change and reform!" the name of Hamas' parliament list.

Reflecting the group's growing confidence, a new poll showed Hamas deadlocked with the ruling Fatah Party. The results were the latest sign of trouble for Fatah, which had dominated Palestinian politics for decades.

Hamas is best known abroad for the scores of suicide bombings it has carried out and its commitment to the destruction of Israel. But it has won over voters by focusing on internal issues, pledging to clean up government and end lawlessness in Gaza. Fatah has been weakened by the chaos and corruption in its ranks.

Friday's Hamas rallies vividly illustrated the differences between the two parties. While Fatah has been riven by disarray and infighting, Hamas has been a model of discipline.

Tens of thousands of worshippers exited mosques across Gaza after noon prayers to attend the Hamas rallies.

In Gaza City, people wore green baseball hats and scarves in support of the group. Hundreds of youths marched in formation holding Hamas flags as music played in the background.

"They try to apply pressure on Hamas to give up the resistance and the weapons," said Ismail Haniyeh, who heads Hamas' list of parliament candidates. "Today we are here to say that they have failed."

Similar gatherings took place in the Jebaliya refugee camp in northern Gaza and Khan Younis in the south. Candidates and top Hamas leaders were scheduled to address the crowds, and participants took oaths pledging allegiance to the group.

During the election campaign, Hamas candidates have generally adopted a conciliatory tone, focusing on a clean-government agenda, and being evasive about whether the group would renounce violence.

But during Friday's rally, Haniyeh made clear that the group remains committed to destroying Israel and capturing the Al Aqsa Mosque in Jerusalem, the third-holiest site in Islam.

"Hamas' principles cannot be changed and will not be changed," he said. "Hamas will not kneel down."

Abbas has said he hopes Hamas will moderate its positions once it joins parliament or even the Palestinian government. In this case, Israel and the international community will have to re-evaluate relations with the Islamic group they consider a terrorist organization.

Israeli officials signaled Friday they would be ready to negotiate with Hamas if it renounces violence and disarms after the election.

"If that takes place and happens, then we can consider or reconsider our position regarding Hamas," said Raanan Gissin, a senior Israeli official. "If that does not happen, clearly Hamas cannot be a partner."

He said Israel expects Abbas to disarm Hamas and other militant groups after the election, as required by the U.S.-backed "road map" peace plan.

"We are not going to exonerate him or release him from this obligation," Gissin said. "If he fails to do that, then clearly we will have to reassess the overall situation."

Acting Prime Minister Ehud Olmert said this week he would be ready to restart peace talks if Abbas disarms militants. But Olmert made no direct mention of talking to Hamas.

According to Friday's poll, Fatah would capture 32 percent of the vote, while Hamas would get 30 percent. The survey of 1,000 people by the Jerusalem Media and Communications Center had a margin of error of 3.5 percentage points, putting the two rivals in a statistical dead heat.

Hamas is widely expected to demand a formal role in Palestinian decision-making after the election.

Israel has not said whether it would sever ties with the Palestinian altogether if Hamas sits in the government. The United States and the European Union have said they would have to re-evaluate the hundreds of millions of dollars in annual aid to the Palestinians.

Any peace efforts will likely remain on hold at least until Israel elections in March. New polls published in two Israeli dailies Friday showed the centrist Kadima Party retaining a wide lead over its rivals.

Kadima was formed in November by Prime Minister Ariel Sharon, who broke away from the hard-line Likud Party in an effort to free his hands to pursue a deal with the Palestinians.

Sharon suffered a massive stroke Jan. 4 and is comatose.