As the race for the White House intensifies, Euronews takes a look at what each candidate will mean for Europeans.
Trump has never made a secret of his scepticism for global warming.
Although the United States, under Barack Obama, originally signed the Paris Agreement — which aims to keep the increase in global average temperatures well below 2 °C above pre-industrial levels — in April 2016, Trump's administration gave formal notice on November 4, 2019, of its intention to withdraw from the commitments to the Paris deal.
The agreement, however, provided for a period of one year before any effective withdrawal — that means the US will leave on November 4, 2020, one day after the election.
Professor Anne Deysine, the author of The United States and Democracy, told Euronews that Trump had rolled back some of the US' environmental protections.
But, she added, it would be possible for a Joe Biden administration - who has promised to rejoin the Paris Agreement - to undo Trump's changes.
Biden has also been advocating for "a 100% clean energy economy and net-zero emissions no later than 2050".
The Iran nuclear deal
In June 2015, an agreement to limit Iran's nuclear programme was reached between Tehran, China, Russia, the United Kingdom, the United States, France and Germany, together with the European Union.
The deal provided that, in return for Iran eliminating or cutting its stockpile of enriched uranium, it will get relief from international sanctions.
Trump, however, announced in May 2018 that the United States would withdraw from the "horrible" agreement and reinstate sanctions.
He said they would "work with [their] allies to find a real, comprehensive, and lasting solution" to keep Iran from developing nuclear arms — although there were "no credible indications of activities in Iran relevant to the development of a nuclear explosive device after 2009" according to the International Atomic Energy Agency.
The controversial decision has led to a renewed rise of tensions between the two countries.
Deysine believes there is still time to backpedal on the withdrawal as "Europeans have managed to convince Iranians not to do anything too damaging".
The situation has changed, however, between the time the deal was struck and today, Anne Kraatz, a senior fellow from Open Diplomacy, told Euronews.
As Biden has shown some willingness to revive dialogue with Iranian authorities, claiming the deal "was working", Kraatz said she could not be certain Democrats would reach a consensus on the Iranian deal and ways to handle it — unlike the Paris agreement that they have long and unanimously been supporting.
"Of course the situation is worse today than it was after the agreement was signed but things can be repaired and patched up this would not be the case after eight years," Deysine said.
A EU-US trade deal?
International trade is no small topic in the presidential run.
In 2019, EU members exported €384 billion of goods to the US and imported €232 billion of goods — which equates to €152 billion in a trade surplus for the EU.
Bdo Bipe Advisory economist Anne Sophie Alsif told Euronews that Biden being elected would be "good news as his position is far less nationalist" than Trump's.
It's been four difficult years for EU diplomats with Trump fighting trade deficit and geopolitical disagreements with tariffs.
She explained, however, that Biden has not bothered much with practical announcements when it comes to international trade because of Trump's populist strategy.
While Biden has been praising multilateralism, Trump has been blaming China, amongst others, and has been hammering home his America first rallying cry — which may sound more popular for many Americans.
Not only is Biden believed to grant some relief to his EU counterparts, but he is also expected to redevelop economic relationships through the World Trade Organization — often turned down by Trump.
As for the unborn transatlantic trade alliance between the US and the EU which, has been under growing strain since Trump's election, Alsif is not certain the future president, whoever that is, can revive the talks.
Biden's "internationalism indicates he would move quickly to reconstruct the United States’ badly ruptured relations with many allies, including NATO," wrote Klaus W. Larres in The Conversation.
Trump has frequently criticised his NATO counterparts in Europe, threatening to reduce US contributions if others don't increase their spending. In July he announced 12,000 US troops would be moved out of Germany and reposted to other EU countries.
“We would review all of the decisions that President Trump has taken, including that one,” Antony Blinken, Biden’s senior adviser for foreign policy, told Reuters.
Bien is also expected to take steps to rejoin United Nations Educational, Scientific and Cultural Organization (UNESCO) and the United Nations Human Rights Commission.
Trump had left both agencies for their alleged anti-Israeli biases, pushing his country further into isolation.
Biden also promised to rejoin the World Health Organization.
Trump had formally notified the UN of his intent to withdraw from WHO on July 7, 2020, over claims the agency was "mismanaging and covering up" the COVID-19 crisis on behalf of China.
Kraatz noted, however, reviving international relationships could be eased by Biden's expertise and previous experience as vice president. "He knows everyone in person," she said.