Battle for Bhabanipur: Why are TMC, BJP in constant war mode?

The BJP on Monday lashed out at the Trinamool Congress over the alleged attack on its senior West Bengal leader Dilip Ghosh, accusing TMC workers of carrying out "state-sponsored" violence.

Earlier in the day, BJP national vice-president Dilip Ghosh was pushed and heckled by alleged TMC supporters, prompting his security officer to whip out a pistol in Bhabanipur assembly constituency, where West Bengal Chief Minister Mamata Banerjee is in the fray, as political temperature rose on the last day of electioneering.

Meanwhile,Ghosh demanded deferment of the September 30 by-poll till the situation has normalised, while the Election Commission sought a report from the state government on the incident.

So, why are TMC, BJP in constant war mode?
Are there enough grounds to cancel Bhabanipur bypoll?