Donald Trump’s presidency has been a turbulent ride for America and the wider world.
On Tuesday, Americans have a chance to deliver their verdict on Mr Trump’s two years in office in the US midterm elections.
At stake is the Republicans’ control of US congress – comprising the house of representatives and the upper chamber, the US senate – along with the party’s command of governors’ offices and statehouses around the country.
Here is a guide to what to watch as a night of drama unfolds:
Polls start closing at 6pm EST in Kentucky (11pm GMT), but things will really start rolling at 7pm (midnight GMT), when polls close in Georgia, Indiana, South Carolina and Virginia.
Another wave of numbers will begin coming in after 7.30pm (12.30am on Wednesday) from North Carolina, Ohio and West Virginia. A big chunk of data will arrive after 8pm and 9pm (1am and 2am GMT) when states such as Texas, New York, Michigan and Pennsylvania begin reporting. The 11pm EST (4am GMT) batch of states includes California, home to several competitive congressional races. Alaska, where polls close at 1am (6am GMT) on Wednesday, will end the night.
– Early voting
Much of America has already voted. Based on reports from 49 states, at least 36.4 million people voted in the midterms before election day. In a sign of the growing influence of early voting, 30 states reported exceeding their total number of mail and in-person votes cast ahead of the 2014 midterm elections.
Turnout in midterm elections is typically near 40%, much lower than presidential elections, where turnout has hit around 60% in recent cycles. University of Florida professor Michael McDonald, who studies voting patterns, estimated recently that about 45% of eligible voters could cast ballots this year, a turnout level that has not been seen in nearly a half century.
– Key races
Two congressional races in Virginia could provide an early steer on how things are going: a district in the Washington suburbs represented by Republican representative Barbara Comstock and another in the Richmond area held by Republican Dave Brat.
Mr Trump has struggled with college-educated women in the suburbs and Ms Comstock’s district could be among the Republicans’ first casualties as she faces Democrat Jennifer Wexton. Mr Brat, meanwhile, won his seat by upsetting then-house majority leader Eric Cantor in the 2014 Republican primary. But this time he is facing a serious threat from Democrat Abigail Spanberger, a former CIA officer.
Another district to watch is in Kentucky – the Lexington-area battle pitting third-term Republican representative Andy Barr against Democrat Amy McGrath, a retired Marine fighter pilot. Mr Trump won the 6th District by more than 15 percentage points in 2016, but Ms McGrath has pushed Mr Barr to the edge with the help of sharp campaign ads that went viral.
– Who controls the house?
Republicans have had control of the house of representatives since the Tea Party helped sweep them into power in the 2010 midterms. Nearly a decade later, the party is trying to avoid a “blue wave” that would return Nancy Pelosi and her house Democrats to the majority.
Control of the house is expected to be determined by a few dozen districts, many of them in the nation’s suburbs. Democrats need a net increase of 23 seats to win back control – a number that many Republican officials concede is a very possible outcome.
The house races will offer clues to where Americans stand in 2018 on immigration, guns, health care and gender equality in the #MeToo era, and will also determine who they want to represent them in Washington during the next two years of Mr Trump’s presidency.
– What’s at stake in the senate?
Republicans hold a narrow US senate majority, 51-49, but have a huge advantage in these contests because the battle for control runs mostly through states Mr Trump won in 2016.
Of the 35 senate races, 10 involve Democratic incumbents seeking re-election in states won by Mr Trump, often by large margins. Democrats’ hopes of recapturing the senate hinge on all their incumbents winning – a difficult task – and on flipping seats in Nevada, won by Hillary Clinton in 2016, and a few states that lean towards the Republicans – most notably Arizona, Tennessee and Texas.
Mr Trump covets seats held by several red-state Democrats, including Joe Donnelly of Indiana, Joe Manchin of West Virginia, Claire McCaskill of Missouri, Jon Tester of Montana and Heidi Heitkamp of North Dakota. Strategists from both parties consider Ms Heitkamp the most vulnerable Democrat, but say the senate make-up could be shaped by a number of narrowly contested races, including those in Arizona, Missouri, Indiana and Montana.
The epic clash to watch involves Texas senator Ted Cruz, Mr Trump’s one-time rival for the Republican presidential nomination, who is up against Democratic representative Beto O’Rourke, who has massive campaign funding. Mr Cruz is still considered the favourite – Texas has not elected a Democrat to the senate in 30 years.
The US president has staged a number of rallies across the country, and on election day he will be making a series of media appearances. Mr Trump is well known for his candid views expressed on Twitter, so anyone with a close eye on proceedings will be watching his feed.
A record number of women are on the ballot – and could become the story of the 2018 election.
Two years after Hillary Clinton’s defeat, more women than ever before won major party primaries for gubernatorial, senate and the house races this year. The results could significantly increase the number of women in elected office.
About 235 women won their primaries for the house of representatives, according to the Centre for American Women and Politics at Rutgers University. In the senate, a record 22 women won their primaries, and a record 16 women were nominated for gubernatorial races.
Many Democratic women, including first-time candidates, have said Mr Trump’s election in 2016 motivated them to run for office. The election also follows the #MeToo movement, as well as the massive women’s march after Mr Trump’s inauguration and the pitched battle over the US supreme court confirmation of Justice Brett Kavanaugh.
Women currently account for one fifth of the 535 House members and senators. By next January, that number could change.
– The history makers
The night could witness a generational change in US congress and herald a number of barrier-breaking officeholders.
In New York City, 29-year-old Alexandria Ocasio-Cortez is expected to become the youngest woman elected to congress. In Georgia, Stacey Abrams is vying to become the first black woman to be elected governor in the nation. Andrew Gillum could become Florida’s first black governor, and Ayanna Pressley is the favourite to become Massachusetts’ first black woman elected to congress.
South Dakota representative Kristi Noem could become her state’s first female governor. Vermont’s Christine Hallquist could become the nation’s first openly transgender governor, and Idaho’s Paulette Jordan is trying to become the country’s first Native American governor.
Native American women could also win seats in congress. In New Mexico, former state Democratic Party chairwoman Deb Haaland is trying to become the first Native American woman elected to congress. She could be joined by Sharice Davids of Kansas, a Native American woman who is also attempting to become the state’s first openly LGBT candidate to win a major office.
In Michigan, Rashida Tlaib could become first Muslim woman and first Palestinian-American in congress. She could be joined by Minnesota’s Ilhan Omar, who is also trying to become the first Muslim woman elected to congress along with the first Somali-American elected to the House.
No matter which way the voting goes, Arizona’s senate race expects to make history. Democrat Kyrsten Sinema could become the first openly bisexual senator and the state’s first female senator. If Republican Martha McSally wins, she will become Arizona’s first female senator.
– Voting problems
The elections will mark the first nationwide vote since Russia targeted state election systems in the 2016 US presidential race. Federal, state and local officials have sought to reassure the public that their voting systems are secure.
So far, there have been no signs that Russia or any other foreign agency has tried to launch cyber-attacks against voting systems in any state, according to federal authorities.
Some states have already dealt with voting problems. Voters casting ballots early have encountered faulty machines in Texas and North Carolina, inaccurate mailers in Missouri and Montana, and voter registration problems in Tennessee and Georgia. In other states, including Kansas, polling places have been closed or consolidated.
– Indicted, but elected?
Two Republican members of congress are trying to win another term while facing separate federal charges.
Duncan Hunter and his wife are accused of misspending more than 250,000 dollars (£192,000) in campaign funds on everything from tequila shots to air fares for a family pet. Prosecutors say the couple tried to conceal the illegal spending as donations to charities, including groups for wounded veterans. Mr Hunter faces Democrat Ammar Campa-Najjar in a Republican-friendly district in California’s San Diego area.
Chris Collins is accused of illegally leaking confidential information about a biopharmaceutical company to his son and the father of his son’s fiancee which allowed them to avoid hundreds of thousands of dollars in stock losses.
Mr Collins’ most serious charge carries a potential prison term of up to 20 years. If he wins in the western New York district and is later convicted and forced to resign, a special election will be held.
Texas attorney general Ken Paxton is still under indictment – he pleaded not guilty to two felony counts of securities fraud. But the Republican is favoured to win a second term, helped by a positive assessment from Mr Trump, who singled him out at a recent rally in Houston as doing a “great job”.