Egypt's prominent political forces continue to announce their backing of the recently launched anti-Morsi 'Rebel' campaign, giving a fresh momentum to the defiant initiative.

Egypt's Constitution Party, founded by democracy advocate Mohamed ElBaradei, announced on Thursday its official and "full" support of the petition movement that seeks to collect signatures in favour of a vote of no-confidence in the administration of President Mohamed Morsi.

Officially launched on 1 May, the group said it has collected more than two million signatures in the first 10 days.

In a Thursday statement, the Constitution Party asserted its volunteering members have been at the forefront of the initiative.

"The party plans to open all its offices to the signature-collecting process as well as any other activities, which will help bolster the movement," read the statement.

Al-Wafd Party was also among the most prominent backers of the signature drive. The party also announced it will utilise its offices in holding the campaign's activities.

The April 6 Youth Movement, a powerful actor in Egypt's political scene and a leading force behind the 2011 revolution, had earlier joined the campaign.

April 6 spokesman Khaled El-Masry asserted in recent comments that the new signature drive represented a "peaceful, forward-thinking and democratic means by which to oppose the current regime and reveal the extent of its [declining] popularity among the Egyptian public."

The initiative seeks to collect 15 million signatures in support of a vote of no-confidence in Morsi; outnumbering the 13.2 million votes Morsi won in Egypt's first-ever free presidential polls last year, in which he narrowly beat Mubarak-era Prime Minister Ahmed Shafiq.

Organisers say the petition will eventually be submitted to the country's state prosecutor to follow necessary legal actions.

The campaign hopes to conclude with a million-strong rally outside the presidential palace in Cairo's Heliopolis district to demand snap presidential elections.