After resigning from the government, he became an opposition leader, founding the Gabonese Union for Democracy and Development (UGDD) in 2005 and placing third in the 2005 presidential election.
He owned L'Autre Journal, a newspaper that was published bimonthly and included articles criticizing the government, but it was suspended by the National Communications Council in December 2003 on the grounds that some of its content could "disturb public order".
[4] Referring to his long history of participation in the PDG regime, he asked the people to forgive his past mistakes.
Following Bongo's victory, Myboto and second place candidate Pierre Mamboundou called for a general strike in early December, alleging fraud.
Myboto expressed condolences to his family and spoke respectfully of Bongo, referring to his work ensuring "stability and social peace" in Gabon.
[22] Regarding the organization of a new presidential election, Myboto met with Interim President Rose Francine Rogombé, together with other opposition leaders, on 24 June 2009.
Pointing to his resignation from the government in 2001 (which he said was "not easy" to do), he stressed that in order to discourage the tendency of politicians to try to remain in office "forever", it was necessary to lead by example.
Myboto also said that he would reform the constitution to restore the presidential two-term limit and "end the life presidency in Gabon".
[27] Like the second and third place candidates, André Mba Obame and Mamboundou, he initially went into hiding amidst the violence that followed the announcement of results, although he soon emerged to attend an opposition meeting.
Also included in the new party were three major politicians who ran as independent candidates in the 2009 presidential election: Mba Obame, Casimir Oyé-Mba, and Jean Eyeghé Ndong.
When announcing the UN's creation, Myboto described it as "a historic moment", saying that "for the first time in our country, opposition parties have decided to come together for political change".