First, let’s recall the previous results from Emerson’s Iowa survey in October, as the impeachment effort against Donald Trump heated up. Trump found himself in a virtual tie with all three Democratic frontrunners in Iowa, and edged by Bernie Sanders:

For good measure, let’s also take a look at the state of the primary race at that time:

Elizabeth Warren had climbed into a tie with Joe Biden, Pete Buttigieg had risen to third place, and Bernie Sanders had suddenly declined to 13%. These trends correlated fairly well with those in national polling in the Democratic primary.

Look what happens after two months of Impeachapalooza, however:

President Trump leads all potential Democratic opponents in head to head matchups in Iowa. The President leads Buttigieg by a point 46% to 45%. Against Biden, he leads 49% to 45%, and against Sanders and Warren he leads 50% to 43%. This is a shift from the previous Emerson Iowa poll, in which Sanders lead Trump by a point, and Biden and Warren trailed Trump by two points.

Donald Trump’s job approval has improved slightly among Iowans over the course of the year. The Emerson poll back in March showed a 42% approval and 51% disapproval. In October, 44% of Iowans approved of the job Trump was doing as president and 47% disapproved. In the latest Emerson Poll, 45% approve and 46% disapprove of the job Donald Trump is doing as president. There is a huge disparity in Trump’s approval by gender. Among men, 54% approve of the job he is doing and 36% disapprove. Among women, 36% approve and 55% disapprove.

That’s an impressive turnaround in 60 days, especially considering that Team Trump isn’t really campaigning yet in Iowa. The seven-point gap against Sanders and Warren is well outside any margin of error, and the four-point lead over Biden isn’t within the boundaries of a virtual tie either. Either Trump is gaining credibility or Democrats are losing it in this key swing state. Which is it?

Readers have to scroll rather far down to see this result, and only slightly less far to see the likely reason for Trump’s rebound. As it turns out, Iowans weren’t too enthusiastic about impeachment two months ago, and they’re even less impressed with it now:

With the impeachment investigations reaching a boiling point in D.C., opposition to impeachment in the Hawkeye state sits at 50% while 38% are supportive of it. 12% of Iowans still have yet to make up their minds about the issue. Despite the recent hearings and pressure from the House Democrats, support for impeachment has dropped slightly since the last Emerson Iowa poll in mid-October when 48% opposed impeachment, 42% supported it, and 10% were unsure.

The gap on impeachment doubled in Iowa in the last two months. Democrats needed movement in the electorate for their impeachment project, but this is clearly not the kind of movement they desired. The impeachment at least correlates to the sudden downward movement in support for their presidential candidates in Iowa — and also in other recent swing-state polling. The previous swing-state polling from GOP shops like Firehouse Strategies seems more credible with this Emerson result in mind.

By the way, this isn’t the only dramatic shift seen in this series. Note how well Warren did in this month’s survey:

Warren’s support has collapsed by almost half over the last two months. Bernie Sanders appears to have benefited the most from her fade, with Mayor Pete still in third place close to his earlier level of support. Even apart from Trump, Warren has clearly collapsed in polling since her peak two months ago, not just in Iowa but also nationally. Joe Biden can perhaps breathe a little easier, but only for the primaries.