On Wednesday, Hamas named Mahmoud al-Zahar, from Gaza, as head of the Hamas majority faction in the legislature, which convenes on Saturday for its first session since the group won the 25 January Palestinian election.
Aziz Dweik, from the West Bank, was chosen by Hamas as parliamentary speaker.
As the leader of parliament, Dweik would become interim president, pending an election within 60 days, in the event of the death, resignation or incapacitation of Mahmoud Abbas, the Palestinian president.
The appointments raised speculation that Hamas would choose another of its leaders, Ismail Haniyeh, as prime minister.
Haniyeh is a Gazan who is viewed by Palestinians as a pragmatist who has forged good relations with rival factions.
Hamas on Wednesday said it will put together the next Palestinian government by early March, timing that could help Israeli hawks win back lost support as they head into parliamentary elections.
Hamas officials said the group would stack top government positions with its own people, threatening to trigger an Israeli boycott of the Palestinian Authority.
Hamas, which does not recognise trounced Palestinian leader Mahmoud Abbas' Fatah movement in legislative elections last month.
With a solid majority of seats in the incoming parliament, Hamas is poised to form a new cabinet in the coming weeks, severely impeding Abbas' ability to pursue peace talks with Israel. The new Hamas-led parliament is to hold its first session Saturday.
Mofaz (R) said Israel would not
talk to a Hamas government
Israeli leaders have taken a tough stance towards Hamas, ruling out any talks with the group until it "renounces violence", recognises Israel and accepts existing agreements between Israel and the Palestinian Authority.
Ehud Olmert, the acting Israeli prime minister and the front-runner in the election, said this week that "all contacts" with the Palestinians will be reviewed once Hamas takes office. He also has threatened to cut off monthly transfers of about $50 million (€42 million) in tax money to the cash-starved Palestinian government.
In the US, the House of Representatives voted overwhelmingly to withhold direct US foreign aid from the Palestinian Authority unless Hamas revokes its call for the destruction of Israel.
Lawmakers in the lower chamber of the US Congress approved the measure by a voice vote of 418 to one. The Senate has yet to vote on the measure.
Israeli officials, led by Tzipi Livni, the foreign minister, held the first of a series of meetings to discuss future policy on dealing with Hamas.
Wednesday night's talks touched on tax transfers and other financial issues. The trend is to stop all but humanitarian funding, officials said. Further talks are scheduled in the coming days, they said.
An Israeli newspaper quoted Shaul Mofaz, the defence minister, as saying Israel would not deal with the Palestinians at all if Hamas taps its own people to serve as prime minister and parliament speaker.
Mofaz told the Yediot Ahronot newspaper that if the two posts are filled by Hamas people, "we will not hold any talks with them".
Hamas's unexpected rise to power has shaken up the campaign for 28 March Israeli elections.
A poll shows the Kadima party
holding its popularity
Hamas's official rise to power could benefit right-wing parties such as Likud, which takes a hard line against the Palestinians.
In a TV interview on Wednesday, Benjamin Netanyahu, the Likud leader, pledged to rally international opposition to Hamas.
"It is part of an international obstacle. We need to ensure our future with an experienced and responsible leadership that knows the job," he told Channel 2 TV.
A poll published on Wednesday showed Kadima holding steady with more than twice as many seats as either of its main rivals - Likud or the moderate Labor.
Prime minister candidate
Hamas officials have said they expect the group to announce its choice for the post as early as Saturday or Sunday, after parliament convenes and before Israel holds its own election on 28 March.
With the clock ticking towards formation of a Palestinian government, Livni has summoned advisers for consultations that one official said would focus on "funding for the Palestinian Authority in the Hamas era".
Ismail Haniyeh could become the
PA's new prime minister
Israeli officials have said Israel is trying to persuade donor nations to cut off support for the Palestinian Authority once a parliament dominated by Hamas is sworn in.
The US and Israel hope to isolate a Palestinian government headed by Hamas financially and diplomatically to pressure it to renounce violence, recognise Israel and honour interim peace agreements, the Israeli officials said.
Palestinians receive about $1 billion a year from all donors, and the Palestinian Authority requires at least $100 million a month.
Palestinian officials have said they expect Saudi Arabia, the UAE and other Arab states to increase their support to the authority in the coming months.