Welcome to our Election Update for Monday, Oct. 29! As of 12:00 p.m., the Classic version of the FiveThirtyEight House forecast gave Democrats a 6 in 7 chance (86.4 percent) of taking control, which is roughly where Democrats stood one week ago (86.5 percent).

We have consistently emphasized the importance of Obama-Trump districts — that is, districts that Barack Obama carried in 2012 but that Donald Trump won in 2016. These swingy seats are a key part of the House arithmetic, and as FiveThirtyEight editor-in-chief Nate Silver laid out last week, they may offer more returns for Democrats than Romney-Clinton districts. And the new polls we have in two Obama-Trump districts found very close contests, each in states that could help make or break Democrats’ chances in the House.

In the Iowa 3rd, a survey from Siena College and The New York Times found Democrat Cindy Axne narrowly ahead of Republican Rep. David Young, 43 percent to 41 percent. That finding echoes the previous Siena College/New York Times poll from a month ago, which showed Axne up 1 point. The razor-thin polling makes sense when you consider recent presidential results: Trump won the 3rd by 3.5 points while Obama carried it by a bit more than 4. In the Lite version of our House forecast, which relies only on district and national polling, the 3rd is a toss-up contest where neither candidate has more than a 3 in 5 chance of winning. But the Classic version of the forecast, which includes fundamentals along with polls, rates the district as “Lean D” and gives Axne a 7 in 10 edge. Although it has only four House seats, Iowa could provide Democrats with two of the 23 net seats they need for a majority. The 3rd is the most competitive seat in the state, with the Iowa 1st — another Obama-Trump seat — looking like a Democratic pick-up. (Incumbent GOP Rep. Rod Blum is under an ethics investigation and has trailed Democratic challenger Abby Finkenauer in fundraising and in the polls.)

As for our second Obama-Trump district, two new polls in the New Jersey 3rd found conflicting results but show a tight contest for Democrats looking to take back the seat. Monmouth University’s latest survey found Democrat Andy Kim up 49 percent to 45 percent over Republican Rep. Tom MacArthur, once we averaged the pollster’s different turnout scenarios. But Siena College/New York Times found MacArthur ahead 45 percent to 44 percent. All three versions of our forecast show this race to be a toss-up, with Kim having a slight edge in each. A district that voted for Obama by 4.6 points and Trump by a little more than 6, the 3rd is the most competitive seat in New Jersey based on our forecast. The Garden State is a pivotal piece of the Democrats’ majority jigsaw puzzle, with potentially four Democratic gains, including one other Obama-Trump seat, the New Jersey 2nd, that looks to be a near-certain Democratic win. (The latest polls we have indicate a 19-point lead for Democrat Jeff Van Drew in this open seat.)

These are only 4 of the 21 Obama-Trump districts in the country (and nine are already held by Democrats), so Democrats will need to pick up more than just these seats to regain a House majority. But if polling is any indication, Democrats’ chances look decent in these seats and strong in the House as a whole.