Retired Army Col. Peter Mansoor plans to vote for Hillary Clinton for president this year, but not because the longtime Republican and former top aide to then-Gen. David Petraeus has had a political conversion. He just thinks Republican Donald Trump is too dangerous to be president. “It will be the first Democratic presidential candidate I’ve voted for in my adult life,” said Mansoor, a professor of military history at Ohio State University. Clinton’s campaign hopes that there are many more national-security-minded Republicans and independents who would vote for her, even grudgingly, rather than see Trump win the White House.