General Michel Aoun returned nearly two weeks ago from 14 years in exile in the wake of Syria's military withdrawal, hailed by his supporters and vowing to use his stature to help build a broad opposition alliance.
But opposition figures have been putting together their own election deals that leave him out in the cold.
On Thursday, Aoun lashed out at the opposition and warned that the upcoming elections could return the same faces to parliament.
Aoun called the entire political class corrupt, accusing opposition politicians of betraying their popular base and of coming only recently to their anti-Syrian stances.
"This is an old habit. They are looking for their own interests ... there is a big difference between the people's wishes and the interest of the political class," he said.
"Most of them are responsible for 15 years of corruption and misleading of the country," he said. "They were pro-Syrian all the time and now they are using Syria to scare people and [get them to] vote for them," he said.
Aoun, a former Christian army commander who fought and lost a "war of liberation" against the Syrians in Lebanon in 1989, regards himself as the "real opposition".
He considers other opposition figures to be former Syrian allies who turned on Damascus a few months before - and particularly after - the 14 February killing of former Prime Minister Rafiq al-Hariri.
"There is a big difference between the people's wishes and the interest of the political class"
General Michel Aoun
The general criticised opposition leaders for accepting to go along with a divisive election law under which the balloting will be contested.
The vote begins on 29 May and takes place on four consecutive Sundays.
Aoun did not name the figures he was critical of, but he has been involved in recent days in a public spat with Druze leader Walid Jumblatt and has also been critical of al-Hariri's son, Saad.
"They started by betraying the relations that we have built up for the liberation of Lebanon," he said, without elaborating.
Al-Hariri's electoral list is
expected to win the most votes
There is a widespread agreement among politicians that the election law, drawn up in 2000 at the height of Syrian control, sets voting districts in a way that marginalises many Lebanese groups and boosts pro-Syrian candidates.
The influential Maronite Catholic Church has sharply criticised
the law, saying it brings legislators that are not representative.
Nevertheless, some opposition groups accepted the government's decision to apply the same law in the upcoming elections.
Saad al-Hariri, a Sunni Muslim, had put forward a diverse list of candidates expected to sweep election in Beirut - nine of his candidates have already won by default, standing uncontested. He is also fielding candidates in other parts of the country, and Jumblatt is fielding candidates in Mount Lebanon. His and al-Hariri's blocs are likely to muster a majority in parliament.
The Shia Muslims' pro-Syrian Hizb Allah and Amal groups teamed up for joint tickets likely to sweep votes in south Lebanon and return many of Syria's allies to parliament.
"They are exploiting an emotional state ... to blackmail people"
Aoun accused politicians of trying to make political gains from al-Hariri's assassination. "They are exploiting an emotional state that occurred after the martyrdom of Premier al-Hariri to blackmail people (into voting for them)," he said.
The result of the in-fighting means there are now new divisions in the anti-Syrian camp, which had seen strong unity among Christians and Muslims in rejecting Syrian dominance following al-Hariri's assassination.
The opposition blamed the killing on Syria and its allied government in Beirut, a charge both denied.