The only way to get the Dems to take vote fraud seriously is for Republicans to do a better job at it--preferably with the help of Democrat operatives. Then you will see all manner of support for tough anti-fraud legislation.
A personal anecdote here: Every election, it seems like that after the polls close, the outstate results come in and are posted right quick. The city of Detroit, on the other hand, waits until the
rest of the state is done before it starts reporting results.
Terminal incompetence or massive fraud? Either one is a realistic option.