The eldest of the Rajapakse brothers, Chamal, was a backup candidate in case Gotabhaya was disqualified over his dual Sri Lanka-US nationality
Sri Lanka's election commission on Monday agreed to let the brother of former strongman Mahinda Rajapakse stand in the country's presidential election, despite a string of corruption cases against him.
Gotabhaya Rajapakse is frontrunner in the campaign for the November 16 election, even though his bid is widely seen as a front to get Mahinda, who was the country's leader from 2005 to 2015, back into power.
The eldest of the Rajapakse brothers, Chamal, was a backup candidate in case Gotabhaya was disqualified over his dual Sri Lanka-US nationality.
Gotabhaya is facing several cases over corruption allegations and the validity of his Sri Lankan citizenship. He claims he renounced his US citizenship in April.
Rajapakse's main challenger is housing minister Sajith Premadasa, 52.
Mahinda Rajapakse is barred from contesting the election because of a two-term limit. His time in power was marked by the end of Sri Lanka's bloody civil war against ethnic Tamil rebels, and international concerns about alleged human rights violations by Sri Lankan troops.
Mahinda Rajapakse tried to become prime minister after a parliamentary election in August 2015 and ended up as the leader of the opposition.
Should his brother win, Mahinda has said he would become prime minister with greater powers conferred on that office in line with a constitutional amendment introduced over four years ago.
President Maithripala Sirisena had on Sunday made the surprise announcement that he will not seek a second term.
His Sri Lanka Freedom Party (SLFP) will not enter a candidate in the race for the first time since the presidential system was introduced in 1978.
Some 16 million people are eligible to vote in the election.