Then what does it mean to be a Democrat, to you?
If I supported Trump on more than 70% of the issues, I seriously doubt you would ever claim I could call myself a Democrat, right? So then why do you give Manchin a free pass?
Nobody is saying "Democrats are the same as Republicans". Don't argue strawmen. Manchin and Heitkamp are effective Republicans. As Buck himself pointed out, they believe they have to support more conservative positions because their election is coming up in their states that have voted red in recent elections. If they vote against what I believe and support, why would I vote for them?
This issue affects the outcome of elections. Voters like me do not want to vote for a party that takes money from corporations because I know they will then represent those corporations over average American citizens interests. All the Democrats have to do is refuse to take corporate money, refuse to finance their campaigns with super PACs. Only take individual contributions.
I left the Democratic establishment party a long time ago. Democrats will continue to lose elections so long as they accept corporate money.