The answer to the question is that we just don’t know. And Congress cares not at all.
Or perhaps I should focus that to Senate Majority Leader Mitch McConnell and Speaker of the House Paul Ryan care not at all. Or Republicans care not at all.
The New York Times has an article about suspicious problems with voter roll books, particularly in North Carolina. It points out that it’s not clear that the problems arose from hacking, but one of the software companies involved is known to have been hacked.
This is why the screwing-around by the Republican leaders and the idiot Freedom Caucus is so evil. Not only are they threatening damage to their voters and all American citizens, but they are not dealing with things that need attention. I could provide a long list of those – fixing the problems with immigration laws, bringing police forces back to the rule of law, improving the ACA, limiting monopolies, you get the idea.
John McCain makes the point more politely to his colleagues. You can call your members of Congress.