But for Democrats, the Trump bump in the polls is a discomfiting feeling, even if it can be explained. “I take the Trump threat very, very seriously,” said longtime Clinton ally Paul Begala. “While media have covered the reluctance of elites like Speaker Ryan to get on board, the rest of the party has done so with remarkable speed. Meanwhile, Hillary has a lot of work to do to consolidate Democrats.”

Clinton officials said they expect Trump to be a much weaker candidate than Romney was four years ago because of major vulnerabilities among moderate voters who are not broken out in the recent national polls. That self-defined category of voters, they contend, is more likely to be repelled by Trump than average Republicans. One Clinton official quoted a Washington Post/ABC poll that showed 58 percent of all respondents believe Trump was unqualified to be president.

“We know this election will be tight, just as most every general election is,” said Clinton spokesman Brian Fallon. “But Donald Trump is no ordinary Republican nominee. He is viewed as unqualified to serve as president in the eyes of huge swaths of the electorate, and for good reason.”

Several Democratic strategists said Clinton will have to win at least 55 percent of moderates, in addition to turning out her base, to win the election.