Even after a convention that critics panned, Trump got a big bounce. Will Clinton gain now too?

Donald Trump has gotten a significant boost from his party’s nominating convention last week; now, Hillary Clinton will try for her own.

Clinton and her supporters won’t know for several days how much Thursday’s acceptance speech will improve her standing with voters — polls lag behind the events they measure because gathering accurate data takes time.

In Trump’s case, the post-convention bounce started to show up in a significant way on Sunday in the USC Dornsife/Los Angeles Times Daybreak tracking poll of the presidential race. The boost continued to build for several days and Trump now holds a 7-percentage-point lead, 47% to 40%.

That represents a significant convention bounce — not a record, as Trump recently claimed, but a larger boost than candidates have averaged recently. Bill Clinton’s 1992 convention holds the record for the biggest bounce, as much as 14 points in some polls.

Already, Trump’s increase in the poll has leveled off, but the full impact of the Democratic convention won’t show up in the poll for days. That’s because the Daybreak tracking poll presents a seven-day rolling average of responses. Four days of the current week took place before the Democratic convention started.

Regardless of how voters ultimately respond to the Democratic gathering, Trump’s success in the poll so far provides a cautionary note about convention analysis.

The GOP convention, particularly its first couple of days, got widely panned. Big-name speakers were absent, divisions within the party were on full display and ratings were tepid. In the end, however, the poll indicates that little of that mattered to voters — most of whom watch only snippets of either convention.

What may have mattered more was Trump’s own speech, in which he laid out a powerful, if pessimistic, assessment of a country headed in the wrong direction and asserted, “I alone can fix it.”

That message appears to have connected with Trump’s main voters, consolidating his support among groups that have favored him for months. 

Compared with his standing before the convention started, Trump has gained significant ground among voters older than 65 and those without a college education — two groups that have been at the core of his support and among whom he holds double-digit leads. 

By contrast, even with the post-convention bounce, Trump has not gained ground this week among college-educated voters.

Among blue-collar white voters, those without a college degree, Trump holds a 59%-24% advantage, but among white, college-educated voters — a group the GOP has carried in every election since World War II, even Democratic landslides — Clinton is running even with him.

Nor has Trump improved his standing among voters in their 30s, 40s and 50s in the last week.

He improved his standing among white voters, but not with African Americans or Latinos, among whom he continues to trail badly.

That leaves a significant opening for Clinton — if she can take advantage of it.

Election 2016 | Live coverage on Trail Guide | Sign up for the newsletter  

Clinton’s speech tonight follows generally well-reviewed appearances by Michelle Obama, former President Bill Clinton, President Obama, former New York Mayor Michael Bloomberg and others.

Those speeches have generated strong attention from Americans: Ratings for the first two nights of the Democratic convention have substantially surpassed those for the equivalent nights of last week’s GOP gathering and are also running ahead of the levels from Democrats’ 2012 convention.

Democratic strategists believe the convention has been largely successful so far at conveying their intended messages — a positive one about what they see as Clinton’s lifelong commitment to improving conditions for children and families and a negative one that portrays Trump as “unsteady” and lacking the temperament or knowledge to be president.

The convention has “unified the party” to a great degree and has “created a permission structure for potential new voters” who have been pondering whether to step onto the Clinton train, said David Axelrod, a former senior advisor to Obama.

In a few more days, we’ll start to learn how many of those voters have accepted the Democrats’ invitation to come aboard.

David.Lauter@latimes.com

For more on Politics and Policy, follow me @DavidLauter

MORE FROM POLITICS

Anti-corporate sentiment doesn't slow down the party scene for lobbyists and lawmakers in Philadelphia

Trump aims at voters he already has, betting they will give him a November win

Hillary Clinton has all kinds of policies — that's the problem as she seeks a coherent message

UPDATES:

2:50 p.m.: The story was updated with poll results about blue-collar voters.

The story was originally published at 1:30 p.m.