The Congress, with 44 members, is the second largest party in the Lok Sabha. However, it falls short of the 10 percent mark -- 55 members in the 545-member house -- which the ruling Bharatiya Janata Party (BJP) has cited as mandatory as per rules for getting the Leader of Opposition status to its leader in the lower house.
"We are the single largest party and we have a pre-poll alliance. Hence, we are entitled to get the post of leader of opposition in Lok Sabha," Sonia Gandhi told reporters in parliament.
Asked what action she would take if the government refused, Gandhi said: "Let's see."
Congress sources had earlier said the party was considering the option of going to court if its leader in the Lok Sabha is not recognised as Leader of Opposition in the lower house.
Earlier in the day, Parliamentary Affairs Minister M. Venkaiah Naidu said that the issue of Leader of Opposition was not raised in the all party meet held before the budget session of the new government.
"No one raised the issue of Leader of Opposition at the party meet," Naidu told the media after the meet.
The budget session of parliament began Monday, with the rail budget scheduled to be presented July 8 and the general budget July 10.
He added that the government has no reservation on any issue and is open to discussion.
"We are willing to discuss each and every issue depending on its national importance and also the admissibility of the same by the respective presiding officer," Naidu said.
The meet was attended by Prime Minister Narendra Modi, Home Minister Rajnath Singh and Finance Minister Arun Jaitley.
(With agency inputs)