Heidi M. Przybyla

USA TODAY

Hillary Clinton faces a fierce general election battle against Donald Trump, according to recent polls, but one group remains unconvinced: pollsters.

Trump, who just secured the delegates needed to clinch the Republican nomination, is in a statistical tie with Clinton, according to the most recent ABC News/Washington Post and NBC News/Wall Street Journal polls.

In separate interviews, the pollsters who conducted those surveys cautioned that much of the tightening in the race comes from Trump consolidating the Republican vote. Meanwhile, Clinton remains in a contentious primary battle with Vermont Sen. Bernie Sanders.

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Further, Sanders’ voters, especially those under the age of 30, are fuming over a superdelegate system they consider unfair and a Democratic National Committee chairwoman they believe has favored Clinton, among other grievances.

But history suggests these Sanders backers are likely to align with Clinton in the end, both pollsters said. Skepticism over the latest Clinton-Trump numbers is further fueled by a Bloomberg Politics survey showing Trump trailing Clinton by 7 percentage points among middle-income voters in the Rust Belt states that will be pivotal to Trump's chances in November .

Sanders’ voters are so angry, according to the latest ABC data, that 20% say they’d vote for Trump over Clinton.

Sounds serious, until it’s compared to the same timeframe in the 2008 primary between Clinton and then-senator Barack Obama, when a slightly larger share of her voters, 24%, said they’d vote for the Republican candidate, John McCain.

That didn’t happen, says Peter D. Hart, a Democratic pollster who conducts NBC’s surveys along with a Republican counterpart. Given Trump’s deficits with women and minority voters, Clinton would need just a fraction of Sanders’ voters to change their minds in order to reopen her sizable lead over Trump, he said.

“There is something that unites Bernie’s voters, and that is they really detest Donald Trump,” said Hart. Just 11% have a positive feeling and 81% have negative feelings about the real estate mogul. “Those people are going to walk in the door pretty quickly because they love Obama, they hate Trump and they’re overwhelmingly Democratic,” he said.

Sanders’ voters are also highly motivated to vote, he said. “The idea that somehow they’re just about to walk away from the voting process does not hold water,” said Hart.

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Much like Clinton’s voters in June 2008, Sanders supporters are “in a snit” and “annoyed” that their candidate is about to lose the nominating contest, said Gary Langer, the pollster who conducted the ABC poll. “It’s not the ideal time to ask them their preference in a general election,” he added.

"By October of 2008, we were not talking about Clinton/McCain voters and by October of this year, we will not be talking about Sanders/Trump voters in any way large enough to impact the election," concurred Bill McInturff, Hart's Republican polling counterpart.

What’s more instructive at this stage, Langer said, is Clinton’s wide lead over Trump on a number of leadership attributes, such as experience, temperament and realistic policies. While they are essentially tied on a number of them, Trump leads on just one: bringing needed change. Clinton also bests him by double digits on many policy issues, including looking out for the middle class and handling international crises. Trump leads on taxes and has a slight edge on trade.

“It’s really more important to look at the candidates’ personal favorability, their attributes, and their policy positions,” said Langer. “Those will tell us a lot more about how voters are coming to their decision.”

The greatest risk to Clinton is if Sanders’ young voters stay miffed. In March, Clinton led Trump 64% to 25% among voters under the age of 30, in line with Obama's past support, according to the ABC poll. Now, that demographic is virtually tied between Clinton and Trump.

“Her single greatest loss of support from March to today is young adults under 30,” said Langer.

Polls show Trump and Clinton in dead heat

There’s no guarantee Sanders voters will come home to Clinton in the way hers did for Obama in 2008. That’s particularly true given that Clinton offered Obama a full-throated endorsement in early June of that year, while Sanders sees himself as the leader of a populist movement more focused on pushing Clinton as far as he can on his top issues. He’s already pledged to take his battle at least to the July convention in Philadelphia.

Yet, with just 70% of Sanders’ voters in her pocket, Clinton’s lead would shoot back up 7 to 9 points over Trump, Hart estimates.

“Typically, when a party is in the midst of or only recently recovering from its primary campaign there are bruised egos and bad feelings,” said Langer.

“The Republicans are over their nominating contest and starting to heal their wounds,” he said.

For the Democrats, their healing process has not begun, said Langer. But “people usually revert to their partisan predispositions.”

Elections 2016 | USA TODAY Network