Donald Trump said last week he hasn’t really started campaigning in the general election. It shows in his poll numbers.

After weeks of blistering news coverage, the latest round of national and battleground-state polling underscores the hole in which Trump now finds himself: trailing Hillary Clinton by a significant margin with fewer than 100 days remaining until early voting begins in the key swing states of Ohio and Iowa.

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Two new, major national polls released Sunday morning — surveys from ABC News/Washington Post and NBC News/Wall Street Journal — differ to some degree, but both are consistent with the broader trend: Clinton holds a reliable lead over Trump, an advantage that occasionally swells to double digits.

Trump now trails Clinton by 6.3 points in the latest RealClearPolitics polling average, and by 6.6 points in the HuffPost Pollster model. In the key states in the Electoral College, POLITICO’s Battleground States polling average shows Clinton ahead by 4.3 points. And perhaps even more important, Trump is lagging behind on a number of other key indicators, including candidate favorability.

At this point four years ago, Mitt Romney was essentially tied with President Barack Obama, trailing by just four-tenths of a percentage point. With the exception of 1988, no candidate in modern presidential history who trailed by this much in June has come back to win.

Trump’s deficit comes after he closed the gap with Clinton last month, when he pulled even after eliminating Ted Cruz, John Kasich and his other GOP rivals for the nomination. But his standing now is worse than that of the four previous Republican nominees in June of the election year.

Already, Trump’s slide in the polls is having a practical impact on his campaign, contributing to declining confidence in the first-time candidate’s ability to remain competitive with Clinton — and spawning a fledgling movement to unbind delegates who could possibly deny Trump the Republican nomination at next month’s national party convention.

Clinton’s now-consistent lead over the past month raises an important question for Republicans: Is the cash-strapped Trump campaign, which is allowing tens of millions of dollars of attack ads from Clinton and her allies to go unanswered, wise to preserve its resources for the post-conventions phase of the campaign? Or do the emerging Clinton advantage and sustained attacks represent a locking-in of voters against Trump?

Sunday's public surveys provided further confirmation of that Clinton lead. Nationally, an ABC News/Washington Post poll showed Clinton leading Trump by 12 points, 51 percent to 39 percent, equaling her largest lead in any telephone survey since both candidates became their parties' presumptive nominees. Clinton's lead in the NBC News/Wall Street Journal poll out Sunday is smaller, 5 points, but Clinton has now led the past 11 polls conducted by live telephone interviewers.

That included surveys out last week, including a Monmouth University poll that showed Clinton leading Trump by 7 points, and a CNN/ORC International poll that gave her a 5-point advantage. In the battleground states, Quinnipiac University polls released last week showed Clinton opening up a lead in Florida, erasing a slight Trump advantage in Ohio and the race remaining neck-and-neck in Pennsylvania.

Trump appears unconcerned by the movement away from him over the past month, telling The New York Times last week, “I haven’t started yet.” But Clinton has: Starting late last week, the presumptive Democratic nominee launched a six-week television ad blitz that includes more than $20 million spread out over eight battleground states. And that's backstopped by the pro-Clinton super PAC, Priorities USA, which is spending in those same eight states, with plans to expand into a ninth state, Pennsylvania, after the Independence Day holiday.

The divergent strategies are reminiscent of four years ago, when President Barack Obama and his allies spent the late spring and early summer hammering GOP nominee Mitt Romney — with an inadequate answer from Romney’s forces.

Those attacks had little impact on the horse race. Romney was able to mount some response, and polls showed him tied with Obama this time four years ago. But the messages conveyed in those attacks did drive down Romney’s favorable ratings and set a narrative that would dog the former Massachusetts governor for the rest of the campaign, according to Neil Newhouse, Romney’s pollster.

“They didn’t move the ballot [test], but they moved our image,” Newhouse said. “The ballot wasn’t moving, but other stuff was, which made it harder to move the ballot later on. It began to frame that election early on, and we couldn’t do a darn thing about it.”

Many of those other measures point to trouble for Trump. In the Monmouth poll, Trump’s favorable rating is just 28 percent, with 57 percent having no opinion of him. Clinton’s was better, though still easily net-negative: 36 percent favorable versus 52 percent unfavorable.

The CNN/ORC poll showed a smaller gap in their image ratings — Trump’s were negative-19 among registered voters, compared to Clinton’s negative-15 — and a 55-percent majority of voters said they expect Clinton to win the general election this fall.

Still, there were some positive numbers for Trump in the CNN/ORC poll. Respondents said Trump would better handle a number of key issues, like the economy and terrorism. (Clinton was rated higher on foreign policy and immigration.)

“Does Hillary have a small but significant lead? Yeah, she probably does,” said Newhouse. “What I find really interesting in the surveys, [Trump] wins on strength, he wins on protecting us, he wins on the economy, and most importantly, he wins on change.”

But the balance of indicators, starting with the ballot test, point to a Trump deficit at this point of the campaign. That puts the New York real-estate mogul behind the pace of the past four GOP nominees. In addition to Romney tying Obama at this stage of the campaign, June was when John McCain began to fall behind Obama four years prior. George W. Bush and John Kerry traded the lead during June 2004, and most polls in June 2000 presaged the close race between Bush and then-Vice President Al Gore.

There are some countervailing signs in the data about the extent to which the nature of the race could change. Newhouse said the fact both Clinton and Trump are disliked by majorities of voters suggests the ballot test could bounce around over the next four-and-a-half months. “I think we expect to see a lot of movement,” he said.

But Patrick Murray, the Monmouth University pollster, suggested the widespread — and, in many cases, intense — disapproval of both likely nominees points to a less-elastic electorate.

“I think that probably close to 9-in-10 voters are locked in,” Murray said. “That’s because their feelings about either or both of these candidates are so incredibly strong, or they’re going to move there.”

And only one candidate is investing real resources to move and reinforce those numbers.

“I think Clinton’s lead is actually fundamentally larger than what the polls show now because of where the candidates stand on their personal attributes,” Murray said, pointing to Clinton’s less-woeful favorability ratings.

Political science research suggests, intuitively, that polls become more predictive closer to the election. But that's particularly true over the course of the summer months, especially following the parties' national conventions.

Columbia University professor Bob Erikson, who co-authored a book that tracked the movement in polls over the timelines of presidential elections going back to 1952, said Trump is behind at this stage of the campaign, "but the gap is not that great, and it could be overcome."

"Both candidates are very well-known and not so well-liked," Erikson added, comparing it to the 1980 campaign, "when Reagan was seen as something of a right-wing extremist, and Carter wasn’t too popular."

In that campaign, June was the month when Ronald Reagan surpassed Jimmy Carter in the polls, though then-Rep. John Anderson (R-Ill.) was taking more than 20 percent of the vote as an independent candidate. Anderson ultimately drew only 6.6 percent.