As of yesterday, it appeared that though polls in the presidential race were tightening, Hillary Clinton was still holding on to a comfortable lead in the six “firewall” swing states that would protect her electoral vote majority.

But a series of polls released today suggests Clinton may have a burgeoning problem with one of those firewall states — New Hampshire.

1) A poll from WBUR/MassInc shows Donald Trump winning by 1 point, with 40 percent support to Clinton’s 39 percent.

2) A Suffolk University/Boston Globe poll shows a tied race, with the major candidates at 42 percent each.

3) And a poll from American Research Group showed Trump winning by 5 points.

Now, ARG isn’t known as the most reliable pollster, so take its outlier results with a grain of salt. And note that a poll conducted last week by WMUR/UNH showed Clinton with a healthy 7-point lead, so she’s still (barely) up in the state’s RealClearPolitics polling average.

But taken together, today’s three New Hampshire polls look like a dramatic change in a state where Clinton had previously led every single poll conducted since July. Perhaps this tightening helps explain why the Clinton campaign just scheduled a visit to the state from President Obama for Monday, the day before Election Day.

Clinton could win with Nevada instead of New Hampshire

Any deterioration in what had been considered the firewall is unmistakably bad news for Clinton.

However, the one silver lining for her here is that New Hampshire is the smallest and therefore least important state of the six. If this series of polls had come out in any of the others — Michigan, Wisconsin, Colorado, Virginia, or Pennsylvania — there would be far more reason for Clinton to panic.

Indeed, since only four electoral votes are at stake in New Hampshire, there appears to be a ready substitute for it if it truly does slip away — Nevada, which has six electoral votes up for grabs.

Polls have shown an extremely tight race in Nevada, so it generally hasn’t been considered part of the firewall. But early voting has been taking place in the state for some time, and Nevada politics guru Jon Ralston has argued that the geographic and partisan statistics he’s seeing so far look “ominous for Trump.” (Nevada is notoriously difficult to poll, and polling averages underestimated President Obama’s eventual margin of victory by 4 points in 2012 and 6 points in 2008.)

If Clinton does lose New Hampshire, holds on to the rest of her firewall, wins Nevada, and loses the other competitive contests, the electoral math would look like this:

That’s a win, of course — but it’s definitely not the scenario the Clinton campaign was hoping to see at this point.

Watch: The bad map we see every presidential election