As the race for the next Karnataka chief minister heats up, all eyes are on the Congress' top leadership here on their pick for the top post in the southern state.

After the Congress party staged a stupendous victory in the May 10 assembly polls, intense lobbying for the chief minister's post in Karnataka started between former Chief Minister Siddaramaiah and KPCC president D K Shivakumar.

The three central observers deputed by the Congress on Monday returned to the national capital after speaking individually to the newly elected MLAs.

The observers will hand over the report on the views expressed by all the newly elected MLAs to party president Mallikarjun Kharge soon.

Kharge is likely to take a decision on who will be the next chief minister of Karnataka soon. He is also likely to hold consultations with top Congress leadership, including Sonia Gandhi and Rahul Gandhi.

Meanwhile, the party is also gearing up for preparations for making the swearing-in ceremony of the chief minister a big show of strength, where several opposition leaders will be invited.

With Siddaramaiah and Shivakumar both staking claim to the top post, they are lobbying hard for it with supporters of each one raising the pitch in support of their leader.

A poster war by supporters of both leaders also erupted soon after the party won the election.

Kharge had appointed former Maharashtra chief minister Sushilkumar Shinde, party general secretary Jitendra Singh and former AICC general secretary Deepak Babaria as observers for the election of the CLP Leader of Karnataka.

The three leaders along with AICC general secretary in-charge of Karnataka Randeep Surjewala left Bengaluru for Delhi and will meet Kharge soon.

The observers spoke individually to all the newly elected MLAs and sought their opinion on who should be the chief minister of the state.

They spoke to all the MLAs after dinner at a private hotel on Sunday night and completed the process late at night.

Earlier, during the meeting of the Congress Legislature Party in Bengaluru on Sunday evening the MLAs passed a one-line resolution authorising the party president to appoint the CLP leader in the state who would be the next chief minister.