I'd say that Democratic Party policies aren't that attractive.
Take the Democratic Party response to the rust belt. Their approach is to offer to retrain people for new jobs and to advise people that they may have to relocate to get a good job - and even then it may not a certainty that the person will get a job. That sounds risky and hard. President Trump had a much more popular message - he'll get your old job back for you. For sure it's a flat-out lie but it's what people want to hear.
Or how about Democratic Party policy on taxation. The Democratic Party would like to move towards a balanced budget by increasing taxes on those people best able to pay them whilst at the same time reducing military spending and making more money available for health and welfare. The GOP policy is far more attractive. They will reduce taxes until an economic miracle becomes inevitable and everyone becomes rich. For sure it's a flat-out lie but it's what people want to hear.
How about healthcare ? The Democratic Party would like to properly fund the ACA but that's expensive and is running into headwinds because there are a lot of people out there who don't want spongers (a.k.a. anyone other than themselves) benefiting and who say their insurance premiums rise (even though they always rose before and at least now they actually have some functionally useful insurance). President Trump has promised much better healthcare for less money which is a much more popular message. For sure it's a flat-out lie but it's what people want to hear.
Democratic Party policies are well thought out and are very often perfectly feasible. They also exist in the real world which means there are complications and grey areas which make people uncomfortable. The GOP OTOH offer simple (albeit completely unachievable) solutions to complex problems - it's an enticing message.
In order to lose weight, would you rather eat less, improve your nutrition and do more exercise or would you rather take a magic pill which simply melts the extra weight away while you sleep ? That first option sounds hard

people would much rather take the second option - even though it's a complete con.