Donald Trump s Republican issue just got a lot harder. After 50 prominent Republican security expert denounced the Republican nomine as a threat to national security, a GOP member of the United States Senate has finally, after much speculation, come out and said what s music to every Democrats  ears.Susan Collins, a moderate member of the GOP from Maine, has come out and pledged that she will not be voting for nor endorsing Donald Trump, after months of withholding an endorsement pending a change of heat from the presidential nominee. Talking to reporters, Collins said plainly:I will not be voting for Donald Trump for president. This is not a decision I make lightly, for I am a lifelong Republican. But Donald Trump does not reflect historical Republican values nor the inclusive approach to governing that is critical to healing the divisions in our country.While touching on Trump (and Bernie Sanders ) resonating campaigns that struck a nerve with millions of Americans who feel disenfranchised, Collins ultimately came to conclude that Trump  rejecting the conventions of political correctness is different from showing complete disregard for common decency  by  shedding the stilted campaign dialogue  has left her with no other option.One major reason Collins decided to back out of endorsing Trump was his attack on military personnel and their families, like her colleague John McCain.To Collins, Trump isn t just advocating for an abolition of political correctness, he s engaging in a full on assault on decency. And it s that boisterous arrogance that is turning off millions of decent, honest, Lincoln-Republicans like Collins.Collins joins her Independent colleague Angus King is deciding to forgo a Trump endorsement, representing a state that traditionally goes Democratic in presidential elections. Collins is also now the second Republican in the Senate to come out and refuse to support Trump indefinitely, no contingencies.Thank you, Senator Collins, for standing up to Trump and his bigoted, shameful scam of a candidacy. And special thanks for standing up the bully pulpit used by Senate Majority Leader Mitch McConnell, who has been desperately trying to herd his sheep of senators to get behind Trump.Featured image via Alex Wong/Getty Images