Warum Im ?
Im Wahlkampf wurde Digitalisierung kaum diskutier. Why is it here Im Wahlkampf?
Here's some useful information
Example: 'Der Frosch, The frog.'
'Ich bin in DEM Frosch. I am in the frog.' The Der goes to dem because when you're in something it is dative but I don't think this counts for when you go into something.
Like jzsuzsi said
Im = in dem. Therefore
'Ich bin IM Frosch.' I am in the frog
'There you have it. This applies for words that use das and der but not for words that use die.