McDermott was already likely to run against Visclosky - who has had some scandals IIRC - and I suspect internals showed a competitive race.
Local from Lake County chiming in here on all of this for some background:
Lake County is one of the few places in the country that still has an old-school Democratic Machine. It's basically a low-key extension of Chicago, with none of the really affluent reformist neighborhoods (so imagine the south and west sides of Chicago + the south suburbs and some rural areas).
McDermott has effectively been the closest thing to the boss of the Lake County Democrats since Rudy Clay retired and Karen Freeman-Wilson said she was going to focus primarily on her city than on county politics. This transfer of the political center of power from Gary's city hall to Hammond's city hall was almost perfectly timed with Hammond's population surpassing Gary's in the 2010 Census.
McDermott, to his credit, has been a very effective mayor. He has made many tangible improvements to the city during his tenure; even if Hammond's population has continued to decline, it is nowhere near as bad as the losses of the 1970s and 80s, or Gary's continued plunge into the abyss. Hence his strong electoral record: winning 52% - 48% in both 2003 and 2007, to winning 82% in 2011 and 78% in 2015 (can't find 2019 because I am GDPR-ed out of the Times of Northwest Indiana, tragically).
However, he has a very abrasive and somewhat authoritarian personality. He is very used to getting his way, and often plays the shadowy, indirect, nasty low-down politics. He's nice when you are on his side, but if you cross him, you are in for a really bad time.
I have met McDermott many times as a member of the Lake County Democrats, and he knows my face but not my name since I was just a precinct captain and student at Purdue Northwest. His chief of staff, Africa Tarver, was the boss of my boss when I worked at the Hammond Development Corporation. Again: nice guy if you're on his side, but can be incredibly nasty and aggressive if you cross him. Also has some...questionable ties to the business community with projects that have been undertaken while he has been mayor.
Also not sure about the competitive polling assertion. We've known for the past decade or so that Visclosky has been getting tired and worn out; he never stuck me as a lifer. I expected he would have retired in one of the past few election cycles, so it's surprising he stayed on this long. McDermott is also probably getting bored of being Mayor and
de facto boss of the Lake County Democratic Party, and wants to move up since he has secured his legacy and there is no serious opposition to him in the County (Gary's new mayor, Jerome Prince, also looks to follow Freeman-Wilson's path of focusing on Gary and its problems).
When May 5th comes around, I am voting for Mara Candelaria Reardon, state rep from Indiana's 12th House district (Munster, Highland, northern parts of Dyer and Schererville, and a large chunk of southern Hammond). She's is a much more solidly liberal candidate and a true friend of labor. She also has legislative experience and is personally a much nicer person.
Right now it seems that this race is going to come down the McDermott versus Candelaria Reardon. McDermott is wildly popular in Hammond and has a lot of goodwill across the Lake County Democrats, but also has his enemies. Candelaria Reardon is much more consistently liked, even if not as well known (but still well known). Her representing the densely-populated southern parts of Hammond for 14 years (save 2015-2017) also negates some of McDermott's home-turf advantage, but to what extent remains to be seen.
You may also remember her as the one of was part of a group of women (Democrats and Republicans) who accused IN AG Curtis Hill of sexual harrassment at a party in 2018.
I wouldn't really be mad if McDermott ended up being the Representative, but he fulfills a lot of the worst stereotypes about Lake Country Democrats and his abrasive style and his being used to getting what he wants means he would not be a very productive or constructive Representative. Considering how bad things have been in Lake County for the past 40 years, we can't afford that; we need our Representative to be able to do everything they can for us and not waste time and resources on petty feuds. I would vote for him for Mayor but never for U.S. Representative.
Candelaria Reardon is definitely the preferable choice here, without a doubt.
