Oh yes! This has happened on expected lines. JD(s) has lost its footing in Karnataka. In the recent assembly elections, they got just 13.3% vote share, which is almost 5% less than what they got last time. Basically, the thing is, JD(s) is loosing its vote share since the last 3 elections. They need someone(BJP) to keep staying relevant in Karnataka politics at least, if not Indian politics.
BJP needs JD(s) to secure Vokaliggas vote. It is a win-win situation.

Moreover, the contest has become bipolar, the recent assembly elections is a proof of it. Now, this proved to be beneficial for INC in the asssembly elections, but it will be better or BJP in the general elections.