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Poll numbers indicate Clinton's campaign has good reason to believe their convention was well-received

But Clinton's campaign is worried that high poll numbers could lull voters into a false sense of security

CNN  — 

New polls that suggest Hillary Clinton has built a significant lead over Donald Trump in the wake of the Democratic convention are being viewed with skepticism by both the campaign and some key Clinton supporters.

Their concern? A belief that the numbers could dip – and could lull voters into a false belief that her campaign doesn’t need their support with the election still months away.

“There’s a reason they call the convention bounces a ‘bounce.’ They can shoot you up to an artificial high and then come down to reality,” explained Clinton communications director Jennifer Palmieri, a longtime veteran of presidential politics. “We are really glad that our convention was so well-received but believe that we continue to face an electorate that is still very divided and know this election will be close.”

Clinton’s campaign has good reason to believe their convention was well-received. A nationwide Fox News poll released Wednesday found the former secretary of state enjoying a 10-point lead over Trump, while national polls out Thursday by McClatchy-Marist and NBC/Wall Street Journal also find Clinton with a wide lead.

Senate Minority Leader Harry Reid, speaking to reporters after introducing Clinton at a campaign event in his home state of Nevada, said he is worried Democrats could become “overconfident.”

History suggests Democrats have reason to be wary.

A chart put together by the American Presidency Project at the University of California Santa Barbara, shows a number of Democrats with sizeable convention bounces who went on to lose in November, including Jimmy Carter in 1980, Walter Mondale in 1984 and Michael Dukakis in 1988.

Republicans Barry Goldwater and John McCain suffered similarly.

One thing that Reid sees as significant in this election is that President Barack Obama also has seen an improvement in his approval ratings, up to 54%, his highest numbers since his second term began. Democrats are hoping the President’s improved position will help him encourage the so-called Obama coalition – the younger and minority voters who gave him eight years in office – to support Clinton.