After a tumultuous few weeks in the presidential campaign, Democrat Hillary Clinton’s lead over Republican rival Donald Trump stands at five percentage points, according to a new Wall Street Journal/NBC News poll, but the race is essentially tied when third-party candidates are included.

The latest survey, of 1,000 registered voters, shows Mrs. Clinton gets 46% support, to 41% for Mr. Trump, in a head-to-head matchup. The presumptive Democratic nominee’s number has held steady over the past month, while Mr. Trump’s standing...