Donald Trump maintains a narrow lead in the polls for the US election.
The former president leads the incumbent in several swing states, which could be critical to securing the White House in November.
Concerns about Joe Biden’s age and the cost of living could work in Mr Trump’s favour as he bids to become the first person to return to the White House after an absence since the 19th century.
But Mr Trump must first win over the moderate Republicans who voted against him in the primaries.
Immigration has emerged as one of the most important election issues as the US faces a growing crisis with record arrivals at the border with Mexico.
Mr Biden is coming under fire from Republicans for overseeing a record rise in illegal migration, while Mr Trump has ramped up his attacks.
The Republican has claimed Mr Biden’s handling of the border had resulted in a “bloodbath” and personally blamed him for the death of Laken Riley, an Augusta University student allegedly killed by an illegal migrant.
In an increasingly polarised United States, the fate of democracy itself has also emerged as one of the key political issues.
Those on the Left feared the threat came from the prospect of the re-election of an authoritarian Mr Trump. Republicans argued that the Biden administration was weaponising the judicial system to convict the former president.
Inflation remains a key issue too, with the cost of living growing despite the economy performing strongly. This is likely to damage Mr Biden in the long run.
Meanwhile, the Democrats are having success attacking Mr Trump over abortion, after the former president packed the Supreme Court, which overturned Roe v Wade.
Mr Trump blamed the issue on a disappointing performance by the Republicans in the 2022 midterm elections, in which several candidates he had personally endorsed failed to make inroads.
Although he takes credit for the “miracle” of undoing Roe v Wade, he also acknowledges that the issue could hurt Republicans at the ballot box and steered clear of imposing a federal limit. Instead, he said he will leave it to the states to make the decision.
Mr Biden has said he will guarantee federal abortion rights if he wins in November, while his campaign has accused Mr Trump of stripping away reproductive rights.
The latest surveys showed that the majority of voters disapprove of Joe Biden.
Polls also show that about two-thirds of Americans think the president, who celebrated his 81st birthday on Nov 20, is too old to continue in the White House beyond next year.
Analysts have suggested the president is losing the support of core Democrat voters, including young liberals, black voters and Muslims concerned about Gaza.
The Reuters/Ipsos poll showed that nearly two-thirds of respondents thought that America was on the wrong track.
However, a Suffolk University/USA Today poll found that the president was gaining ground on the economy.
In October, 21 per cent of voters said the economy was recovering and this figure had climbed to 33 per cent by March.
Voters have not been happy with his handling of the Gaza crisis according to a New York Times/Siena poll.
It found that 46 per cent of voters trusted Mr Trump to handle the crisis and only 38 per cent had confidence in Mr Biden.
Mr Trump’s poll ratings appear to be unaffected by four criminal indictments against him, for alleged election interference, mishandling of classified documents and claims he paid hush money to a porn star.
In April, he became the first US President to stand criminal trial, appearing in Manhattan Criminal Court over “hush money” allegations.
He has frequently complained that his time in court – four days a week while it is in session – means he cannot campaign in vital swing states. However, he has used the media spotlight to claim he is the victim of a “witch hunt” by Joe Biden and the Department of Justice.
Mr Trump has also taken to the stand to testify in a $250m civil fraud trial in New York, which threatens to strip him of his business empire in the city, including the iconic Trump Tower.
His appearance makes him the first former president in 100 years to give evidence as a defendant in court.
Mr Biden and Mr Trump romped to victory in the primaries, sweeping almost all states with limited opposition.
Mr Trump faced the sternest test against Nikki Haley, who lasted until Super Tuesday before dropping out.
Major questions remain over whether her more moderate supporters will be willing to back Mr Trump, who ended up underperforming according to a comparison of polls and results.
Exit polls from Super Tuesday also showed an alarming number of Republican voters saying Mr Trump will not be fit to serve if convicted.
Mr Biden, meanwhile, is facing a backlash over support for Israel among more Left-wing, young and Arab voters, all of whom have traditionally swung Democrat.