"It looks that the High Command lacks faith in my leadership and since they have not taken me into confidence to nominate candidates to contest the Legislative Council election, I have tendered my resignation," he told reporters.
Reports reveal that Siddaramaiah submitted his resignation to Party President, Sonia Gandhi and state party chief G Parameshwar, after his loyalist former Union Minister CM Ibrahim was denied nomination.
He said that Ibrahim was promised candidature earlier by the High Command but they later nominated candidates without consulting him.
"Whoever occupies an honourable post in a democratic set-up should uphold the dignity of the post," he said.
"Once I have tendered my resignation, there is no question of going back," he said.