For years, the imposing black gate that sealed the border between Egypt and Gaza symbolized the pain and isolation that decades of conflict have wrought on this tiny coastal strip, especially under Hamas in recent years.

But recently, the gate has come to represent a new turn for the increasingly confident Hamas leadership. The twin arches of the border crossing have swung open twice in recent weeks for V.I.P. arrivals, first to receive hundreds of Palestinian prisoners from Israeli jails as one captive Israeli soldier moved in the other direction, and a second time for Egypt’s Muslim Brotherhood to visit Gaza for the first time in decades.

Both instances lifted the fortunes of the Islamists at a critical time ahead of negotiations scheduled to be held in Cairo this week with their main rival, President Mahmoud Abbas of the Palestinian Authority, who leads the Fatah party.

Hamas’s leader, Khalid Meshal, arrives at those talks with a sense of regional winds at his back. Dictators have fallen, replaced by protest movements and governments that include the Islamist movements those dictators suppressed. Hamas has lost no opportunity to highlight this development as it basks in the growing regional importance of its parent organization, the Muslim Brotherhood, the oldest and most powerful Islamist movement in the world.

“This is a hot Arab winter that has not until now ripened into spring,” a Hamas official, Dr. Mahmoud Zahar, proclaimed in Gaza last month as he claimed the Arab revolutions for Islamic revivalism. The campaigns to oust corrupted leaders have reached a “critical stage,” he said, before concluding, “With God’s help, next year we will see the flowering of Islam.”

Mr. Abbas, by contrast, arrives with mixed success for his plan to gain United Nations recognition of statehood for Palestine. He has gained huge domestic support — polls are 80 percent in his favor — but the bid has faltered and he has alienated a crucial ally in Washington.

Hamas, on the other hand, trumpets its success in trading one captive Israeli soldier, Sgt. First Class Gilad Shalit, for more than 1,000 Palestinian prisoners, hoping that the Egyptian-brokered exchange will erase Palestinians’ memories of the increased isolation and blockades that Gaza suffered during Sergeant Shalit’s captivity.

Boaz Ganor, an Israeli security analyst and the founder of the International Policy Institute for Counterterrorism, believes that Hamas is now “much stronger” than it was before. The Shalit deal, he believes, was part of a “very detailed, sophisticated plan” by Hamas, which the United States and the European Union have labeled a terrorist organization, to break free from its Gaza enclave and secure greater legitimacy “at least in the international arena, if not in the eyes of Israel,” before Palestinian elections, scheduled for May.

“As long as they were holding an Israeli soldier against the Geneva Conventions and so forth, they would not be regarded as a legitimate candidate,” he said.

Both Hamas and Fatah leaders say that the Cairo talks will focus on setting up a unity transitional government of technocrats to take Palestinians through to elections, already long overdue.

Nabil Shaath, a member of Fatah’s Central Committee, said that the talks would focus on unity, nonviolence and finding a cabinet and a prime minister acceptable to both sides. He said there was now a “much better opportunity” for agreement. Hamas had enjoyed success with the prisoner swap, and Fatah gained domestic support for the statehood bid, he said, and “success reduces the need for competition.”

The statehood effort would benefit from reconciliation, he said, because among the “major critiques” that Mr. Abbas faced at the United Nations was the Palestinian Authority’s lack of control over Gaza.

Hamas’s momentum is not just confined to Egypt, where relations between the ruling military council and the Muslim Brotherhood have soured in the uprisings of recent days, but where the Brotherhood remains a powerful force before — and almost certainly after — elections scheduled to begin on Monday.

There is also sign of a thaw between Hamas and Jordan, which recently dropped its objection to allowing Mr. Meshal to visit Amman, Jordan’s capital, from his base in the Syrian capital, Damascus, and Jordan’s prime minister, Awn Khasawneh, declared that Jordan’s decision to shut down Hamas’s headquarters in Amman in 1999 was a “political and constitutional mistake.”

But Hamas does face difficulties. For one thing, the opening to Jordan remains fragile. The Jordanian leader, King Abdullah II, paid a visit to the Ramallah headquarters of the Palestinian Authority this week, a high-profile confirmation that he still regards Mr. Abbas as the leading figure in Palestinian politics.

Critics of Hamas also point out that it is a Sunni Arab movement that has received financial and political support from Iran, which has a Shiite non-Arab government. Having its headquarters in Damascus also puts it in a delicate position. Both Syria and Hamas are backed by Iran, but President Bashar al-Assad’s crackdown on dissent in Syria has killed at least 3,500 people, including many of Hamas’s Muslim Brotherhood colleagues.

“I think Iran would be happy if Hamas supported Assad’s regime, but I don’t think Hamas can do this because they classify themselves as freedom fighters, so they cannot stand with Assad against freedom fighters,” said Waleed al-Modallal, a political scientist from Gaza.

But Nathan Thrall, a Jerusalem-based Middle East analyst with the International Crisis Group, sees opportunity in the fact that both Palestinian parties are at odds with their backers.

“For years, Palestinian reconciliation has been encumbered by claims from Fatah that Hamas’s leadership is subject to an ‘Iranian veto’ and from Hamas that Fatah’s leadership is subject to an American one,” Mr. Thrall said. “In the last several months, both parties have suffered a serious deterioration in relations with their patrons. That gives some people hope that factionalism might now be overcome.”

On the streets of Gaza and the West Bank, Hamas’s prisoner exchange and Mr. Abbas’s statehood initiative were both widely popular moves, which both sides have sought to promote heavily. But it is not yet clear that either development will prompt people to change their allegiance.

In the Balata refugee camp, a Fatah stronghold in the West Bank, Muhammad Zubeidi, 23, conceded that the prisoner release was a coup for Hamas. “The day of the release was the first time for years that I have seen Hamas flags in Balata camp,” he said. “It might affect the decision of the families who got their loved ones back, but I think people will vote Fatah.”