Democrats, the traditional party of trade unions, is likely to back President Donald Trump's trade war with China, especially for their hoped-for effect on helping American workers.
The US president took credit for his Republican Party's gains in the Senate, casting those results in historic terms.
Sessions says in a letter to Trump that he resigned at the president's request.
Despite the Republican Party's mixed results in the election, true adherents to Trumpism claimed wins in various states at multiple levels, a sign that the president's influence remains strong among his core voters.
Democrats said Republican lawmakers will no longer be able to protect Trump from a watchful Congress.
After an initially muted reaction from financial investors in the United States and globally, European stock markets turned higher and S&P and Dow Jones futures followed, gaining as much as 0.7%.
Fifty-five percent of women said they backed a Democrat for the House this year, compared with 49% in 2014.
Trump tweeted that the midterm elections - in which Democrats defeated his Republicans to control the lower house of Congress for the first time in eight years - were a tremendous success.
Democratic Minority Leader Nancy Pelosi is expected to become speaker of the House, a position she held for four years from 2007, when she made history as the first woman ever to rise to that post.
US networks project that Democrats will gain the 23 seats needed to win a house majority, but Republicans have struck back in Indiana and North Dakota, and held on to at-risk seats in Tennessee and Texas.
The 29-year-old has championed her working class and Puerto Rican roots, moonlighting as a bartender until defeating a Democratic grandee in a party primary earlier this year, capturing imaginations around the country.
Americans vote today in critical midterm elections that mark the first major voter test of Donald Trump's presidency, with control of Congress at stake.
One of the most expensive and closely watched Senate races is in Texas, where incumbent Republican Senator Ted Cruz is facing Democratic Representative Beto O'Rourke.
At stake are all 435 seats in the House of Representatives, 35 seats in the 100-member Senate, 36 governor's posts and seats in state legislatures across the country.
From the danger of Democratic Senate candidates losing their seats in Missouri to duelling female candidates in Arizona, the US midterms elections will see a number of interesting contests.
Oil prices and the dollar also feel the wrath.
The online ad features courtroom footage of Luis Bracamontes, an illegal immigrant from Mexico convicted in the 2014 killings of two police officers in Sacramento, California, saying in accented English he would kill more cops.
Democrats, while still favoured overall, have been unable to build a decisive edge over Donald Trump's Republicans.
A frequent critic of Trump, Bloomberg has donated US$80 million to help Democrats gain control of the House of Representatives and US$20 million to help Democrats running for US Senate, which Republicans now narrowly control 51 to 49.
Swift's comments got 1.5 million likes on her Instagram page. Model Chrissy Teigen, actress Blake Lively and singer Perry were among those adding 'likes' to Swift's post.
Exhausted and embittered, the 100 members of the upper chamber of Congress acknowledge that their once-venerated institution plumbed new depths during the contentious fight that ended Saturday with Kavanaugh's confirmation.
The 28-year-old pop star says while she has been 'reluctant' to share her political views in the past, she has changed her mind.
A final vote could come Saturday on President Donald Trump's embattled candidate, who if approved would seal a conservative majority on the nine-seat court for decades.
Kavanaugh denies the incident occurred, calling it 'a smear, plain and simple'.