Mr Haya (left) and Mr Abu Marzouk continued to voice reservations
Hamas officials in Cairo say they will meet representatives of the rival Fatah movement this month to discuss the timing of fresh Palestinian elections.
Senior officials from Hamas, the militant movement in control of Gaza, made the announcement after talks with Egypt's intelligence chief in Cairo.
Egypt hopes the Palestinian groups will reach a reconciliation agreement including elections and other reforms.
But analysts say there are few signs of a narrowing of their differences.
Egypt has proposed establishing a government of technocrats acceptable to all factions, re-organisation of the Palestinian security forces, and new parliamentary and presidential elections.
Hamas official Moussa Abu Marzouk said the factions would form technical committees to discuss the issues.
"The committees will take their time, one or two or three months, these are issues that cannot be resolved in days or weeks," the Damascus-based Mr Abu Marzouk told reporters.
Another offical, Khalil al-Haya from Gaza said: "We in Hamas accept that elections are on the table for discussion."
However, he expressed opposition to simultaneous presidential and parliamentary elections for the Palestinian Authority.
A Fatah official accused Hamas of stalling and said their positive reaction to the Egyptian plan was an attempt to buy time so they could consolidate control over the Gaza Strip.
"They still have illusions that they can impose on others their will to have Gaza as an independent entity under their control," Azzam Ahmad told Voice of Palestine radio.
On paper, PA President Mahmoud Abbas - who is also leader of Fatah - ends his term in office on 8 January 2009.
The parliament - which is controlled by Hamas - is currently scheduled to remain in power until January 2010.
Hamas MPs have demanded Mr Abbas hold presidential elections before 8 January, and said they would no longer recognise his legitimacy after that time.
Correspondents say this would deepen the already-protracted rift.