Has the race tightened up — or have pollsters simply adjusted to a relatively stable status quo that has been in place for a while? Reuters becomes the latest among pollsters to find the race tightening in the last week of the election, making the upcoming Election Day considerably more suspenseful than it seemed three or four weeks ago:

The race for the Oval Office tightened significantly in the past week, as several swing states that Republican Donald Trump must win shifted from favoring Democrat Hillary Clinton to toss-ups, according to the Reuters/Ipsos States of the Nation project.

The two presidential candidates are now tied in Florida and North Carolina, and Clinton’s lead in Michigan has narrowed so much that the state is too close to call. Ohio remains a dead heat and Pennsylvania is now tilting to Clinton.

What, exactly, constitutes “tightening”?

The States of the Nation project estimates Clinton’s odds of winning the needed 270 Electoral College votes at about 90 percent, down from 95 percent last week. If the election had been held on Wednesday, the project estimates, she would have had 256 solid electoral votes and an estimated final tally of about 302 votes, to 236 for Trump. Last week, she had 278 solid votes and a final tally of 320 votes, to 218 for Trump.

By any measure, however, Trump has had a good run in the past week. He has seen his support grow in 24 states while losing ground in 11. Conversely, Clinton’s support grew in 13 states while shrinking in 22.

Going from 95% to 90% odds of winning the election doesn’t sound like a significant tightening at all. It sounds more like a margin-of-error adjustment. However, Reuters isn’t the only oddsmaker seeing things shifting either. Nate Silver writes at FiveThirtyEight that New Hampshire provides a good bellwether on the changing electoral winds, and that Hillary’s weak firewall is now at risk:

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 agocould 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.

The odds at FiveThirtyEight actually have tightened, although they’re still not good for Trump. On October 17th, Trump’s chances of winning the election based on Silver’s polling analysis and other factors was 11.9%. Less than three weeks later, they’ve almost tripled to 33.5%. That still leaves Hillary as a strong favorite to win at 66.5% or 2:1, but that’s down from almost 8:1 in mid-October.

How much of this is real, and how much of this is pollster adjustments to fine-tune their final results? Politico’s Stephen Shepard wonders too:

First, public pollsters don’t apply controls to their samples for partisan inclination. That’s a point of contention: Public pollsters argue that partisanship isn’t a fixed trait and using it as a demographic parameter could predetermine the result the poll is designed to measure.

But campaign pollsters argue that this is a cause of much of the volatility — especially in states where historic turnout rates of registered partisans are relatively consistent. And when partisan inclination bounces around from poll to poll — especially around major news events — it’s mostly a function of voters choosing not to respond. In other words, when there’s bad news about Donald Trump, like his poor debate performances and the leaked audio of Trump describing how he gropes women, Republicans are less likely to participate in polls.

On the other hand, when the news is dominated by stories about Clinton’s email scandal, Democrats don’t want to respond to pollsters. …

Ultimately, with the volatile national polling and inconsistent state polling, most practitioners are focused more on their own private data — even though public polling can shape coverage of the race in the final week.

Yesterday I spoke with RealClearPolitics’ Sean Trende, who believes that the shifts seen in the last three weeks are real. Whether we’re seeing a stabilized view of the race now, or more shifts will come in the final days, remains to be seen. At the very least, the suspense for Tuesday’s results has heightened, even if the fundamentals of the race may not have changed as much as people have thought over the past couple of months.