Islamic Jihad and Hamas had in the past objected to joining the mainstream PLO, opposing its peace moves with Israel, but recently have softened their stance and agreed to a temporary halt to attacks against the Jewish state.
In a meeting late on Sunday, Palestinian President Mahmud Abbas agreed to Islamic Jihad members taking part in a meeting of the PLO executive this week to help cement the 17 March truce, Islamic Jihad leader Muhammad al-Hindi said on Monday.
Al-Hindi said both his group and Hamas would attend the PLO session "to discuss a basis on which the PLO should be rebuilt" and said the PLO would consider an effort to let them join the organisation.
Abbas, a moderate elected in January, said after the Gaza meeting that he was seeking to further "national unity and calm" with the groups.
"It is necessary to follow up these issues with them so that we can push forward calm and the political process," or peace talks with Israel, Abbas said.
Aljazeera reporter Walid al-Umari said Abbas' meeting with Islamic Jihad leaders covered results of the recent Palestinian factions' meeting in Cairo, the issue of calm with Israel, national unity, Palestinian elections as well as the feasibility of Islamic Jihad and Hamas being integrated into the PLO.
Hamas, whose prominent role in a 4 1/2-year uprising against Israel has enhanced its popularity, announced plans to run in a parliamentary poll in July after boycotting the first such elections in 1996.
"It is necessary to follow up these issues with them so that we can push forward calm and the political process"
Islamic Jihad has not decided whether to stand in the polls.
But news reports said it might revise its previous boycott announcements, al-Umari said, adding that all Palestinian factions appeared to be leaning towards participation in the elections to consolidate national unity.
Abbas, in remarks broadcast on Sunday, said Fatah plans to conduct primaries to pick its candidates for the July elections.
"The last time, Fatah had no serious competition. This time there is competition," Abbas told Al-Arabiya in an interview.
"The last time, Fatah had no serious competition. This time there is competition"
"Fatah is interacting internally. The new generation wants to rise up... The question is how to ensure them a role?
"We will resort to primaries, to ask the Fatah grassroots who they want to field for the elections. We will not impose on them anyone they don't want," he added.
Fatah young guards have been demanding reforms since Hamas' strong showing in municipal elections earlier this year. The resistance group, which opposes peace with Israel, won 30% of all seats in local elections in the West Bank and a majority of seats in Gaza.
The 120-member Fatah Revolutionary Council, the second most important decision-making body in the group, was meeting in the Gaza Strip to discuss the reforms, seen as crucial to prepare for the elections.
An opinion poll published this month showed support for Fatah had dropped to 36% from 40% in December, while Hamas' popularity had grown to 25% from 18%.
Fatah has suffered from public perceptions of high-level corruption, mismanagement and internal divisions pitting moderates against militants and a long-entrenched old guard against a younger generation demanding democratic reforms.