Bangalore: Karnataka coalition partners Congress and Janata Dal Secular on Friday formally announced they would contest the next general election, due next summer, as a pre-poll alliance.

The declaration comes a day after a united Opposition defeated the BJP in two parliamentary by-elections, in BJP-ruled Uttar Pradesh and Maharashtra, giving itself an incentive to stitch together a larger unity before the Lok Sabha polls.

"It has been decided that the Congress and the JDS will fight the next Lok Sabha elections as a pre-poll alliance," the Congress general secretary in charge of Karnataka, K.C. Venugopal, said at a news conference.

He said the decision followed discussions among senior leaders, including Congress president Rahul Gandhi and JDS national president H.D. Deve Gowda.

Sources said the shares of the state's 28 Lok Sabha seats would be worked out later. In 2014, the BJP had won 17 of the seats, the Congress 9 and the JDS 2.

The Congress and the JDS had contested the May 12 Assembly elections separately but formed a post-poll alliance to keep out the BJP, which had emerged the largest party in a hung House.

Asked whether the alliance portended "something bigger" at the national level, with more parties coming together to take the BJP on, chief minister H.D. Kumaraswamy said: "I expect Karnataka to be the place that would usher in the required change ahead of the general election."

He added: "Yesterday's election results showed what's in store for 2019. This is the first stage of a trend (of Opposition unity) that will gain momentum in a big way."

On Friday, the Karnataka coalition partners also finalised the distribution of portfolios, an exercise that has taken nine days since the May 23 swearing-in. The allies had already agreed on 22 ministry berths for the Congress and 12 for the JDS, but the delay in cabinet formation had caused embarrassment.

Venugopal announced that the Congress had conceded key portfolios such as finance, public works, power and transport to its partner. Finance had apparently been the sticking point. Venugopal said Rahul had decided to give it to the JDS in the interests of a stable government.

"Rahul Gandhi said this coalition government was the need of the hour for the nation and asked us to take appropriate decisions in the larger interest of the country," Venugopal said.

He said a common agenda for governance would be chalked out at the earliest.

A "coalition coordination and monitoring committee" will be formed under former chief minister P.C. Siddaramaiah of the Congress. JDS national secretary Danish Ali will be the convener of the committee, which will include the chief minister, deputy chief minister G. Parameshwara (Congress) and Venugopal.

The committee will be the sole clearing authority for all appointments to statutory boards such as the ones for milk, sericulture and agriculture.

Two state spokespersons will be appointed, one from each ally, to address the media jointly.