United States President Donald Trump’s approval ratings have fallen to a record low, a sign that Americans angry about rising living costs amid the deeply unpopular US-Israel war on Iran could punish his party at the upcoming midterm elections.

Most Americans are unhappy with Trump’s performance, according to a Reuters/Ipsos poll published on Monday, with more people saying they plan to vote for Democrats on November 3.

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Sitting US presidents have traditionally seen a dip in approval ratings around the midterms, and that has often coincided with their parties losing seats in Congress.

With Trump’s ratings lower than any of his predecessors, experts say Democrats could reach their goal of flipping both the US House of Representatives and the Senate in the congressional vote.

All 435 districts in the House and 33 of the 100 Senate seats are up for election.

Republicans currently hold a slim majority of 218-214 seats in the House, and are also leading in the Senate, with a 53-47 majority. However, Democrats are campaigning hard to seize majorities in both houses, a scenario that could prove a major headache for Trump.

Here’s what the latest polls might mean for these elections:

What do the latest polls show?

About 31 percent of Americans polled by Reuters/Ipsos said they were happy with Trump’s performance – the lowest-ever figure during Trump’s two terms as president. Two weeks earlier, the number stood at 32 percent.

When asked which party they would vote for if the midterms were held today, 47 percent chose Democrats, while 35 percent opted for Republicans. That represents a 12-point advantage for the Democrats, the widest ever in the current cycle, and is up from the seven-point lead two weeks ago.

The slide in support for Republicans came from the growing number of women choosing Democrats – about half of those polled. More voters – 40 percent – also said Democrats were better at managing the economy, compared with 33 percent who selected Republicans.

The polls, which canvassed 1,679 adults, are a generic ballot providing an overview of voter sentiment, but not a state-by-state breakdown, meaning the results could still be surprising.

What is the history of presidential polling ahead of the midterms?

The president and party in charge of the White House usually face some backlash in the midterms.

Supporters of the non-presidential party are often more motivated to vote in the midterms than their counterparts, according to the University of Virginia’s Center for Politics.

The think tank also found that in 12 of the past 20 midterm elections since 1946, the sitting president’s approval ratings worsened between July and November, the months just before the elections. Only in seven instances did approval ratings improve, while in one case, during the 2006 elections under President George W Bush, the president’s approval ratings stayed the same.

What has that pattern meant for midterm results?

With a dip in presidential ratings being the norm, a more favourable view of the sitting president still often correlates with the governing party losing fewer seats in the midterms, according to researchers.

When presidential approval ratings are much lower, the party in power often loses more seats.

In the 20 midterm elections held since 1946, the governing party lost seats in the House of Representatives in 18 instances, although a well-liked president often cushioned the effect, according to data from The American Presidency Project run by the University of California (UC), Santa Barbara.

For example, Americans’ favourable view of President George Bush – 75 percent in the 1990 midterms – saw Republicans lose only eight seats across the two houses.

But research aggregating the UC Santa Barbara data found that when presidents have approval ratings below 50 percent, their party was likely to have a bad election.

In 1994, for example, when President Bill Clinton’s first midterm approval rating stood at 46 percent, Democrats lost 52 seats in Congress.

But when Clinton’s approval rose to 66 percent by the next midterms in 1998, Democrats lost only five seats.

What does that mean for Trump?

Researchers say Trump’s plummeting ratings amid the US-Israel war on Iran are highly likely to affect Republicans negatively.

With Trump’s generally low ratings – the lowest of any president in US history, according to UC Santa Barbara’s aggregate – researchers say the odds that Republicans will keep their thin majority in Congress are very small.

The question, however, remains just how badly the party could be hurt by Trump’s policies.

Republicans might have some hope yet. According to the Center for Politics, presidential approval in the past five midterms has generally been slightly higher in exit polls than in pre-election polling, because those later surveys include people who have actually voted.

That means the midterm results ultimately hinge on how well parties convince supporters to actually cast their ballots.

How many seats could the Democrats take?

According to NBC News, which conducts its own polling and provides state-by-state breakdowns, Senate Democrats are likely to win North Carolina and Maine from the Republicans. NBC also sees Alaska, Iowa and Texas as states that could go either way.

In the House of Representatives, NBC predicts “possible flips” from Republican to Democrat in 15 districts. It rates four districts currently held by Republicans and three held by Democrats as “toss-up”.

If the Democrats were to win all of those close contests without losing any of their current seats, they would gain a total of 22 seats in the House of Representatives and five in the Senate.