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There’s been a potential breach of Hillary Clinton’s electoral firewall. And it’s come in New Hampshire, a state that we said a couple of weeks ago could be a good indicator of a Donald Trump comeback because of its large number of swing voters. Three new polls of New Hampshire released today showed a tied race, Trump ahead by 1 percentage point and Trump up by 5. There are some qualifications here: The poll showing Trump with a 5-point lead is from American Research Group, a pollster that’s had its issues over the years. And other recent polls of New Hampshire still show a Clinton ahead. But the race has clearly tightened in New Hampshire, with Clinton leading by only 2 to 3 percentage points in our forecast.

If Clinton lost New Hampshire but won her other firewall states, each candidate would finish with 269 electoral votes, taking the election to the House of Representatives. Or maybe not — if Clinton also lost the 2nd Congressional District of Maine, where polls show a tight race and where the demographics are unfavorable to her, Trump would win the Electoral College 270-268, probably despite losing the popular vote.

Couldn’t Clinton win Nevada to make up for the loss of New Hampshire? Or Florida? Or North Carolina? Well … of course she could. All those states remain highly competitive. The point, as we’ve said before, is just that Clinton’s so-called firewall is not very robust. If you’re only ahead in exactly enough states to win the Electoral College, and you’d lose if any one of them gets away, that’s less of a firewall and more of a rusting, chain-link fence.

To illustrate this, let’s compare Clinton’s current position in our polls-plus forecast — which gives her a 65 percent chance of winning the Electoral College — to FiveThirtyEight’s final election forecast in 2012, which gave President Obama a 91 percent chance. How could the model be so much more confident in Obama’s chances than in Clinton’s, even though we projected he’d win by 2.5 percentage points nationally and she’s ahead by 2.8? Part of it is because there are far more undecided and third-party voters this year, which could lead to a last-minute swing, or a polling error, and makes the model more cautious. But Obama’s and Clinton’s chances of winning the popular vote are relatively similar in our forecasts (76 percent for Clinton now, 86 percent for Obama then) despite that. The difference comes mostly in the Electoral College.

In the table below, I’ve run a head-to-head comparison showing how many electoral votes each candidate was projected to have at various margins of victory or defeat. For instance, Obama had a lead in states (and congressional districts) totaling 332 electoral votes in our final 2012 forecast. Clinton leads in states totaling only 272 electoral votes, just two more than the minimum she needs to win the Electoral College. This comparison is slightly unfair to Clinton because we have her down by just a fraction of a percentage point in Nevada, North Carolina and Florida — whereas Obama was ahead by just a fraction of a point in Florida — but you can see how Obama’s position was more secure. For instance, he had 303 electoral votes in states where he led by 2 percentage points or more in our final forecast, whereas Clinton has 272.

CLINTON 2016 OBAMA 2012 FOR STATES WHERE DEM. MARGIN IS … TOTAL ELECT. VOTES STATES CLINTON HAS THAT OBAMA DIDN’T TOTAL ELECT. VOTES STATES OBAMA HAD THAT CLINTON DOESN’T >= -10 points 387 AK SC 399 IN MO MT >= -9 387 AK SC 399 IN MO MT >= -8 378 AK GA 362 MT >= -7 375 GA 359 >= -6 375 AZ GA 348 >= -5 359 AZ 348 >= -4 359 AZ N2 347 >= -3 341 347 IA >= -2 323 347 IA OH >= -1 323 NC 332 IA OH >= _ 0 272 332 FL IA M2 NV OH >= +1 272 303 IA M2 NV OH >= +2 272 303 IA M2 NV OH >= +3 268 CO VA 281 IA M2 NV NH OH >= +4 239 VA 253 M2 NV PA >= +5 190 247 M2 MI MN PA WI >= +6 185 217 M2 MI MN NM >= +7 183 216 ME MI MN NM >= +8 183 200 ME MN NM >= +9 176 190 ME NM OR >= +10 176 178 ME Obama’s position in the Electoral College was more secure M2 = Maine’s 2nd Congressional Distict

N2 = Nebraska’s 2nd Congressional District

Based on FiveThirtyEight’s polls-plus forecast

The differences stem from states with substantial numbers of white voters without college degrees — in particular Ohio, Iowa, Nevada and that 2nd district in Maine. (Granted, Nevada is more diverse than the other states — and it also has a history of bad polling — so I’d be careful there.) Imagine if Clinton were 3 or 4 percentage points ahead in Ohio and Iowa instead of 3 or 4 points behind, and that she were ahead by 5 or 6 points in Nevada instead of tied there. That would make for a much more robust map: losing New Hampshire would not be a problem, for instance, and she could even afford to lose Pennsylvania. Speaking of Pennsylvania, Clinton’s polling lead is narrower there than Obama’s was. It’s also much narrower in Michigan, a state that was barely even a swing state in 2012 but presents a risk to Clinton this year.

What does Clinton get in exchange? She’s polling a little better than Obama was in the highly educated swing states of Virginia, North Carolina and Colorado. But it’s only a little bit better — not a lot better — because African-American turnout for Clinton may be lower than it was for Obama in North Carolina and Virginia, and because third-party candidates may be eating into her margin in Colorado. She also has a much better chance of winning Arizona or Georgia than Obama did. But neither Arizona or Georgia are all that close to the electoral tipping point, and Clinton will probably win them only if she’s having a strong night overall and winning all the other swing states, too.

Instead, many of Clinton’s gains relative to Obama come in states that aren’t competitive at all. Clinton’s margin in our California forecast is bigger than Obama’s was four years ago, for instance. She’s polling better than he is in super-well-educated Maryland and Massachusetts. And then there are her gains in red states. While Clinton’s now very unlikely to win Texas, with Trump having recovered there in recent polls, she’s still likely to make the state a lot closer than Obama did. The same goes for Utah, Alaska and South Carolina. Those could make for some extremely blue maps if Clinton were (unexpectedly at this point) to win in a landslide. But if she’s trading voters in Ohio and Iowa for those in Texas and Maryland, she’s not getting the better side of the deal.

Our Elections podcast is doing daily shows between now and Election Day.