WASHINGTON — In a stark warning for Donald Trump as he eyes a possible general election showdown with Hillary Clinton, Americans trust the Democratic front-runner more than the Republican businessman to handle a wide range of issues — from immigration to health care to nominating Supreme Court justices. Even when asked which of the two candidates would be best at “making American great” — the central promise of Trump’s campaign — Americans are slightly more likely to side with Clinton, according to a new Associated Press-GfK poll. The survey does reveal some potential trouble spots for Clinton.