Commission sources say Gujarat may be asked to file an FIR or First Information Report against Mr Modi.
The law bans candidates from canvassing within 100 metres of a polling area. But, the Election Commission says, it does not stop people from wearing clothes that display a party symbol.
Both the Congress and the Aam Aadmi Party pointed to Mr Modi being seen with a prominent lotus, his party’s symbol, while he voted and as he addressed the media.
Election Commission sources said voters cannot be asked to hide their hands, which is the Congress’ symbol, or, say, put away their spectacles, which is the symbol of the Indian National Lok Dal headed by Om Prakash Chautala.
Aam Aadmi Party leader Ashutosh tweeted today soon after Mr Modi voted, “BJP released manifesto on polling day. Modi did road show on other polling day and now PC (press conference) with party symbol today. will EC react? (sic)”
Congress spokesperson Meem Afzal said, “I think it is a violation of the code of conduct…he held a press conference near the polling booth…His nomination must be cancelled from both the constituencies. He thinks he is above the law and order of the nation.”