Joe Biden's first 100 days in office. The easy part is likely behind him.

US President Joe Biden will celebrate his 100th day in the Oval Office on Friday, a symbolic milestone to review his performance and what it means for the remainder of his tenure.

So far, his approval rating has remained somewhat level since he came into office on January 20 and currently stands at 54.4 per cent, according to poll aggregator FiveThirtyEight. This is 12 percentage points higher than his direct predecessor Donald Trump enjoyed at the same time of his presidency but lower than all the other White House occupants since World War II.

This has been described by most commentators as a sign of the deep political polarisation in the country with Democrats overwhelmingly happy with his performance while the vast majority of Republicans seemingly disapprove.

Here's what he has achieved so far.

More than 42 per cent of the country's 328 million population have received at least one dose of the vaccine — the third-highest rate in the world after Israel and the UK — and the administration reached its target of 100 million shots within the first 100 days of the vaccination campaign a week early.

"For the US there had been a very long period of mishandling the COVID-19 pandemic but the vaccine [rollout] is now looking strong," Susi Dennison, Director of the European Power programme at the European Council on Foreign Relations (ECFR) thinktank, told Euronews.

"What this means internationally is the possibility that the American stock of vaccines is going to become available at some point in the future for more sharing, which is very positive for the global response as well," she added.

The human cost of the pandemic has been particularly dear in the US — it has the world's highest death toll with more than 573,000 lives lost — and the toll on the economy has been harsh as well. The US economy contracted by 3.5 per cent in 2020 — its worst performance since the end of the Second World War.

Biden responded to that with a historic $1.9 trillion (€1.5 trillion) American Rescue Plan handing out cheques to families and businesses and increasing benefits for jobless people, renters struggling to make their monthly payments and food assistance.

Earlier this month, he also unveiled what he billed as a "once-in-a-generation" infrastructure investment plan that would allocate, if passed, a massive $2.3 trillion (€1.9 trillion) to fixing highways and bridges and improving the electric grid and access to broadband internet.

One of the first executive orders Biden signed was to undo Trump's withdrawal from the Paris Climate Agreement.

He has since hosted a global, virtual summit on climate and announced aims to cut US greenhouse gas emission by 52 per cent compared to 2005 by the end of the decade. He also wants the country to become carbon-neutral by 2050.

This US re-commitment to tackling global warming has had the added consequence that several other countries, including Brazil, Russia and China, appear to have toughened up their ambitions, Dennison flagged.

"There was a sort of sense that Trump had been leading a sort of climate denial camp on the international stage that seems to be boiling away now that we're seeing Biden taking a different line. That is indeed positive news but I think the challenge is going to be now how the Biden administration translates that leadership into material action," she went on.

On this front, "the message is clearly that America is back," Sudha David-Wilp, a senior Transatlantic fellow at the German Marshall Fund of the US, told Euronews.

"Biden is just basically restoring America's role in the world, but it will be different. It won't be like it was before, even previous to Trump, but there will be certain principles that he will adhere to like human rights and working with partners using alliances as force multipliers — those are things that are a tradition in US foreign policy," she explained.

So far, this has translated into a new rapprochement with the European Union following years of acrimony under Trump, who loved to hate NATO and railed against European defence spending.

Europeans also appear to be warming up to the US again. A Morning Consult poll for Politico found this week that while most Europeans polled held an unfavourable view of the US under Trump, the trend has been reversed under Biden.

The phenomenon is particularly acute in Germany, where 62 per cent of people held an unfavourable view of the US on the eve of Biden's accession to the White House.

Now, most respondents — 46 per cent now — view the country positively. It is the same in France, Spain and the United Kingdom.

Still, an ECFR poll of 15,000 Europeans found that at least 60 per cent of respondents in every country polled believe their country cannot depend on US support in a major crisis.

"I think that Biden's objective was first to bring stability back to the American people," David-Wilp explained, especially given that the country has been suffering from multiple "calamities all at the same time: economic, public health and even racial strife".

Dennison said that she has "a relatively optimistic assessment" of the remainder of his presidency "from looking at where he decided to put early resources".

But smooth sailing it won't be.

"Domestically it remains a challenge," Dennison said, "with a strong opposition from the Republican side in Congress in terms of moving the big kind of changes" he wants to bring forward.

This polarisation will impact both the domestic and international agenda.

"There is still bipartisanship when it comes to NATO and we see that now with China and Russia. But on Iran, for example, there is hardly any bipartisanship," David-Wilp said. "Even climate, more and more Republican voters are seeing climate change as a problem but I don't think they're cheering Biden's move to rejoin the Paris Climate Accord."

His bid to restore American leadership on the global stage is also likely to be hampered by realities his pre-Trump predecessor did not have to contend with, including increasingly assertive China and Russia.

"The world is not the same as during the last Democratic administration. The kind of tensions (we see) are multiple in nature and have become more evident under COVID," Dennison stressed.