Their differences go back to before the Congress' win in the May 2013 Assembly elections. It intensified when Siddaramaiah became CM, while Parameshwar lost his seat in the polls. The former's critics alleged Siddaramaiah of telling his community voters to vote for Parameshwar's rival.
The rift worsened with Siddaramaiah declining to make Parameshwar deputy chief minister or even a minister in his Cabinet. He has been postponing the matter since he took charge as CM, for one reason or the other. All this bad blood has hurt the performance of the government, say party insiders.
As Siddaramaiah is considered a newcomer in the Congress, having joined only in 2005 after revolting against Janata Dal (S) supremo H D Deve Gowda, many party seniors were unhappy that their claims for the top post were ignored by the high command in Delhi.
There was also Siddaramaiah's unilateral announcement of "Annabhagya", the Rs 1 a kg rice scheme to poor families, waiving of loans and additional subsidy to milk producers, hours after he took the oath of office last year. These were party's poll promises and other seniors felt it should have been implemented after the Cabinet formation, and with Parameshwar and others in the picture.
There is also the complaint that Siddaramaiah favoured his ex-JD-S loyalist with plum posts but ignored many legislators whom Parameshwar recommended for induction in the Cabinet or in appointments to heads of boards and corporations.
"The chief minister can control infighting by expanding the Cabinet and appointing disgruntled MLAs to boards and corporations but he (CM) is keen to appoint only his loyalists to these posts," said a party senior.
Last month, Parameshwar was elected unopposed to the state legislative council, qualifying him to get into the Cabinet. However, Siddaramaiah has been buying time on expanding or reshuffling the ministry.
Accordingly, the CM's opponents have been joining hands to try and replace him. Several Vokkaliga and Lingayat MLAs & MLCs have been complaining to Parameshwar (who's from the Dalit community) that Siddaramaiah was ignoring their community, lawmakers and constituencies.
The grapevine also has it that the CM overlooked many recommendations from Parameshwar or other veterans for transfers or appointments in lucrative departments such as home, excise, public works, revenue and industry.
Parameshwar had got a setback with the recent Lok Sabha elections, when the party won only nine seats in the state, in contrast to his claim of 20-plus. However, a spate of recent crimes against women and question raised on basic policing have given the CM's detractors a lot of ammunition.
The difference of opinion between the two has hurt almost every development in the party and the government. Some legislators have complained to the high command in Delhi and its observer for the state, Digvijaya Singh, against Siddaramaiah. Their main complaint was that he did not take their suggestions in the transfer of government officers in their constituencies. A recent complaint is that the CM has not done much to allay the fears of farmers, worried about drought, with the below-normal rainfall this year.
It is reported that Singh has told both the CM and the party president to resolve their differences and work together, in the interest of the party and the government.
Last month, though, both went to Delhi separately, with different lists of candidates for the Rajya Sabha and legislative council elections. Siddaramaiah was asked to explain to central party leader A K Antony the reasons for divisions within the party.
The next test for the CM will be when he inducts Parameshwar into the Cabinet.