Donald Trump

This Oct. 7, 2016, file photo shows Republican presidential candidate Donald Trump pausing during a meeting with members of the National Border Patrol Council at Trump Tower in New York.

( Evan Vucci, Associated Press)

CLEVELAND, Ohio -- It wasn't that long ago that Ohio appeared to be Donald Trump's to lose.

After he was able to consolidate Republican support, polls in late August showed Trump pulling out a slight, but significant lead over Democratic nominee Hillary Clinton in Ohio. While he still faced an uphill climb nationally, Trump's success in Ohio, which he has maintained for several weeks, fueled speculation that the Clinton campaign had shifted its attention to friendlier battleground states.

But we wondered last week what was going on after two highly respected pollsters found different results in Ohio -- one by Quinnipiac University found Trump leading in Ohio, while the other by Monmouth University showed Clinton with a small lead. We observed:

Additional polling data released since then -- including a fresh poll from Baldwin Wallace University -- has reinforced the Monmouth poll, suggesting Clinton has retaken the advantage in Ohio.

She's led seven out of eight scientific polls released in October. That includes the BW poll, conducted in the immediate aftermath of a historically disastrous weekend for Trump, that shows Clinton leading Trump in Ohio 43 percent to 34 percent.

Why has this happened?

"The short answer is Trump has allowed himself to be Trump, and that's what's caused him to stumble," Tom Sutton, director of BW's Community Research Institute, said Wednesday.

The past few weeks have brought Trump a very bad sequence: his poor performance in the widely viewed Sept. 27 presidential debate, his subsequent feud with a Latina beauty queen whose weight he insulted in the 1990s and the Oct. 2 revelation that he avoided paying federal income taxes for years.

But that all seems mild compared to the Oct. 7 release of a 2005 tape showing Trump making extremely lewd and sexually aggressive comments about women. Rather than simply apologizing for his comments, Trump also tried to argue that Bill Clinton had done worse.

The tape, and Trump's response, set off a cascade of defections from high-ranking Republicans. Trump is now waging historically unprecedented battles with the Republican Party -- including with U.S. House Speaker Paul Ryan -- distracting him from attacking Clinton's record or advancing policy arguments that could win over undecided voters.

Trump's performance in this week's debate was better, particularly in the eyes of his supporters, but may not have done much to sway undecided voters.

The whole episode reinforces long-standing voter concern with Trump's temperament and overall fitness to be president, and has increased the likelihood that mainstream media coverage will focus on Trump's difficulties rather than Clinton or Democrats in general.

So, Trump not only could be turning off undecided voters who might be on the fence, but also actively losing sympathetic voters and demoralizing them about their side's chances of victory.

What groups are contributing to Trump's shrinking lead?

Polls conducted over the past month suggest Trump recently has lost a significant amount of support from two main groups.

First, there's men, which had been a strong base of support. Trump's sizable lead among men had helped compensate for his weakness among women, who likely have been turned off by Trump's history of making misogynistic and offensive comments.

Trump's lead among men had been in the mid-to-high double digits -- as high as +17 in a Suffolk University poll released on Sept. 15. Recent polls have shown that number creeping into the single digits. An Oct. 8 poll by YouGov, which included the day the Access Hollywood tape was released, showed Trump's lead among Ohio men as +2. The Baldwin Wallace poll showed that lead as +3.

Then, there's independent voters. Trump's lead among this group consistently pushed +20 a month ago. That number has shrunk to the high single digits in recent polls, even swinging to +8 in Clinton's favor in the BW poll, although that number is not consistent with other polls.

There's a problem with polling on partisan affiliation, though. Many voters often change their minds about which party they identify with most, especially if they are depressed about their ideally preferred candidate. But it appears Trump's support among self-identified Republican voters could be in trouble too. While there's reason to believe this figure is disproportionately low -- read below -- BW's poll shows Trump's support among Republicans at a dismal 70 percent.

What may have helped Clinton do so well in the Baldwin Wallace poll specifically?

Compared to 2012 Ohio exit polls, a disproportionately high number of the BW poll's respondents were people with college degrees, particularly those with advanced degrees. This would explain Trump's poor performance among Republicans who were surveyed.

"The education level, when you look at it, definitely has an oversampling on the higher end, and that could explain some of the difference," Sutton acknowledged.

Voters with lower education levels tend to favor Trump, while the opposite is true of more educated voters. Ohio has fewer levels of college educated residents than other key swing states, which has contributed to Trump's relative strength here. If Trump can win back these educated voters, who historically have backed Republicans and are more likely to show up on Election Day, it would help him shore up his support.

On the other hand, the poll under-sampled black voters, who overwhelmingly back Clinton. So Clinton's overall +9 lead could be relatively sound.

Update, 2:46 p.m. Oct. 13:

Baldwin Wallace re-weighted their poll to more closely match Ohio's education levels and racial makeup, and got basically the same results. Clinton's +9 lead dropped slightly to +8. Subcategories, like the number of Republicans who said they would vote for Trump, remained almost unchanged.

What's the bottom line?

While things could change, it goes without saying that it's best to be winning polls at this late stage of the election. And given that voters generally begin locking in their decisions around now, and given the state of Trump's campaign, it now seems to be a pretty safe bet that Clinton will win Ohio and with it, the presidency.

Even with the poll's sampling issues, Sutton said it clearly reinforces a larger trend. National polls released this week have shown Clinton extending her lead over Trump, in some cases pushing into the double-digits.

"I think it still shows we have a strengthening lead by Hillary Clinton, and it seems to be in part due to reaction to everything that happened following the first debate," Sutton said.