Washington,  The party in control of the White House is historically known to lose the US congressional midterm elections in the incumbent President"s first term.

President Barack Obama had a word for it when it happened to him in 2010: "Shellacking".

The Democrats, with their man Joe Biden in the White House, are widely expected to lose the House of Representatives thus. The Senate, which is evenly split at present, could either way; both parties need to improve their tally by just one to take absolute control of the body.

Democrats currently control the White House, the House of Representatives (220 to 212, with three vacancies) and the Senate (50-50 and Democrat Vice President Kamala Harris's tie-breaker vote).

The White House is not on the ballot for the November 8 midterm elections. But all 435 seats in the House of Representatives are, as well as 35 of the Senate's 100. Also in contention are Governorships and legislatures of 36 of America's 50 states.

"Midterms are usually a referendum on the sitting President," said Doug Schwartz, Director of the Quinnipiac University Poll, whose election findings and forecast are followed closely in political circles. "Having said that, we have noticed that voters are distinguishing between incumbent Democratic Senators and the Democratic President."

President Biden has been polling badly, and remains unpopular. His approval rating for October was 40 per cent - down from 44 per cent in August, which has been the highest he has reached, according to Gallup polls. Former President Donald Trump was at 42 per cent and Obama was 45 per cent at this time, in October of the second year of their first terms, 2018 and 2010 respectively.

Here is what happened in the 2010 midterm. Republicans wrested control of the House of Representatives from Democrats picking up 63 extra seats. The magnitude of their victory - and the Democrats' defeat conversely - was summed up by Obama as a "shellacking".

Trump fared better, but only marginally. In the 2018 midterm election, Democratic won back the House of Representatives with 41 more seats.

Biden and Democrats were in the shellacking-territory till some months ago, according to pollsters, buffeted by out-of-control inflation, which was exacerbated by oil prices surge due to the Ukraine war, and failure to deliver on his poll promises mainly because of differences amongst Democrats themselves. His approval ratings sank to 38 per cent in July.

Then came a string of legislative victories, headlined by the sweeping Inflation Reduction Act, which cut prescription drugs costs, extended healthcare and marked the most aggressive action taken on climate change ever. And it raised taxes levied on those making more than $400,000 a year.

"Today offers proof that the soul of America is vibrant, the future of America is bright and the promise of America is real," Biden said at an event to celebrate the Act a month after.

Biden's popularity went up to 44 per cent in August.

Democratic party's fortunes saw an uptick at the same time because of a completely unrelated development: the Supreme Court's ruling ending abortion as a constitutional right of 40 years. Even Republicans - some, not all - were appalled. Kansas, a solidly Republican state, voted to protect abortion, defeating a measure that could have restricted or outlawed it.

Democrats now had a national issue, and suddenly it seemed they were ready to beat the precedent of the ruling party losing the midterms. "Pollsters started seeing conditions improving for Democrats, making races more competitive," Schwartz said, adding, "the abortion issue became a key factor in some special elections favouring Democrats".

And that proved to be a short lived bump. FiveThirtyEight, a well-regarded poll aggregator and forecaster noted that Republicans have since "regained much of the advantage they had before" the ruling. And now, the Republican party has roughly a 4-5 chance of winning the House.

The bulk of the 36 states going to polls are expected to re-elect the incumbent Governor or the nominee of the party currently in power. But there are exceptions. Some states could flip. Maryland and Massachusetts are likely to pass from Republican to Democrat Governors, and Republicans could pick up Nevada, Wisconsin, and Oregon.

The most watched gubernatorial races include Governor Ron DeSantis's run for a second term in Florida. He is widely seen as preparing for a White House run for 2024 and a defeat now will be suicidal. The other interesting contest is in Georgia, a solidly Republican state that voted to Biden in 2020 - incumbent Brian Kemp is running for a second term. His challenger is Democrat Stacey Abrams and, to an extent, former President Donald Trump who has openly called for his defeat for refusing to help him overturn the Georgia vote in the 2020 presidential election.