Throughout Donald Trump’s first term in office, the US president has harked back to the Obama years. From blasting the “horrible” Iran nuclear deal to blaming Barack Obama’s administration for the “obsolete, broken system” that Trump claims has hindered the US response to the COVID-19 crisis, he’s used his predecessor as a constant foil.

During his 2016 campaign for the White House, Trump committed himself to rolling back much of the Obama legacy. Now, his 2020 election opponent is Obama’s former vice president, Joe Biden. This ensures that the choice American voters make at the ballot box in November will either reinforce Obama’s legacy – or rebut it once again.

It’s not always easy to pinpoint the exact legacy a president leaves behind, particularly in the short term. Sometimes, political legacies that appear immediately important can diminish in significance over time. Or those that initially seemed flat – such as that of Harry Truman – come to be seen in a much more positive light as the years pass.

For Obama, the successes he enjoyed and disappointments he endured after his election in 2008 were often a consequence of the political environment in which he operated. Once Republicans took control of the House of Representatives in January 2011, the scope for legislative action dramatically diminished and his administration had to find other ways to get things done. Such routes included executive actions as well as presidential memoranda.

During the 2016 campaign, candidate Trump declared that he would “cancel every unconstitutional executive action, memorandum and order issued by President Obama.” Yet, while executive actions are simpler to reverse than legislative achievements, there are still procedural obstacles to overcome if a predecessor’s actions are to be rolled back. And these obstacles were not always given due attention by the Trump administration.

Nor was America’s institutional fragmentation brushed away with a new broom once Trump entered the White House. Like Obama, he enjoyed two years when his party controlled both houses of Congress – until the Republicans lost their majority in the House of Representatives in the 2018 mid-term elections. This limited Trump’s capacity to continue unpicking his predecessor’s achievements.

In a new book, we’ve looked at what kind of legacy Obama left as well as what success Trump has had in trying to roll it back. We’ve found that while some aspects of the Obama legacy were vulnerable to reversal, other areas proved more resilient. The stand-out legacies of the Obama years would become a direction of travel, if not always an end point.

Here we will look at four key areas: healthcare, immigration, climate policy and racial justice.

Healthcare

The standout domestic policy legacy of the Obama administration was the Affordable Care Act (ACA), also known as Obamacare. Enacted in early spring 2010, ACA was the most significant policy reform of the US healthcare system since the 1960s. While the new law built on existing programmes such as Medicare and Medicaid, rather than replacing them, it significantly expanded the government’s role in funding healthcare and the regulation of the private health insurance market.

At the signing ceremony for the bill, Biden was caught on microphone describing the moment as a “big fucking deal”. Republicans agreed with this sentiment and spent much of the remainder of Obama’s presidency declaring their aim to repeal the law. After taking control of the House in January 2011, Republicans passed multiple bills to repeal all or parts of the ACA. But while Obama remained in office, with a power to veto these bills, this remained symbolic rather than substantive politics.

Yet that symbolism mattered. It meant that the law remained contested and that Republican controlled state-level governments, such as Texas with its large uninsured population, did not cooperate with implementing key aspects of Obamacare. When Republicans took control of the White House and both chambers of Congress in January 2017, the outlook for the preservation of Obamacare looked bleak.

But despite Trump’s promises to “repeal and replace” the ACA, it is still the law of the land as his first term draws to a close. In 2017, the Republican-led House passed the American Health Care Act, which would have repealed large parts of the ACA. Although the Republican leadership bent all the Senate’s norms to breaking point, no equivalent legislation passed in the upper house and Obamacare remained.

In fact, the Republican efforts to undo the law seem to have been central to a growth in popularity for the ACA. Throughout Obama’s time in office, a plurality of Americans said that they viewed the law unfavourably, but that shifted once it came under sustained threat and reports emerged of how many people would lose insurance should it be repealed.

It also became clear that the sheer complexity of the law made it difficult to unravel if Republicans were to keep in place its popular aspects, notably protections for people with pre-existing medical conditions. In addition, the new president’s manifest frustration at the complex details of health policy made him an ineffective broker in negotiations.

Efforts have continued throughout the Trump presidency to undermine the application of Obamacare. The administration is backing a court case that will be heard by the Supreme Court a few days after the November election that could bring the ACA crashing down.

Read more: If the Supreme Court strikes down the Affordable Care Act, Trump's health care order is not enough to replace it

Meanwhile, healthcare remains a key battleground in the 2020 election, particularly in the midst of a pandemic. Confounding logic, Trump claims that Biden would threaten protections for Americans with pre-existing health conditions and that these protections will only be preserved if he is re-elected. But these protections exist as a result of the ACA, which the Justice Department is trying to bring down.

A Biden victory along with Democratic control of both houses of Congress would likely see moves to build on the ACA. Medicare for All, a single-payer government funded healthcare plan championed by the senator Bernie Sanders, is not on the Biden agenda. However, it’s possible his administration could introduce measures such as a public insurance option to compete with private insurers in the individual insurance market. In this context, conservatives are probably right to see the public option as a Trojan horse that could open the door to greater government involvement in the provision of American healthcare.

All this means the ACA is an Obama legacy that has proved more resilient than expected when Trump took office in 2016.

Immigration

Obama’s legacy in other areas was more mixed and relied less on legislative action than efforts to use the executive power of the presidency. A good example was immigration. The Obama administration’s promise of comprehensive reform didn’t really come close to making it through Congress, even when the Democrats controlled both chambers.

Obama did use his executive power to introduce the Deferred Action for Childhood Arrivals (DACA) policy in mid-2012. This provided temporary legal status to so-called “Dreamers”, people who had been brought into the US without documentation as children and who were deemed illegal despite many having lived their lives as Americans. A subsequent executive action, which would have granted legal status to a much wider group, never came into force as it was thwarted by the courts in 2016. This left DACA as Obama’s major legacy in terms of immigration policy.

As an executive order it should have been relatively straightforward for the Trump administration to reverse. This seemed especially likely given how Trump had so remorselessly used his antagonism to “illegal immigration” as a campaign tool in 2016.

Trump did in fact express some ambiguous sentiments about the plight of the Dreamers, but in September 2017 he labelled DACA an “amnesty first approach” and declared that the protections the programme offered would start to be rolled back in six months. Yet in the summer of 2020, the Supreme Court ruled that the administration’s effort to reverse DACA was so fumbled as to fail to meet the relatively straightforward administrative procedure required to do.

Read more: Supreme Court ruling on Dreamers sends a clear message to the White House: You have to tell the truth

This makes the 2020 election even more critical – especially for those people living in America who don’t have a vote. The Trump administration would surely try again to rollback DACA if re-elected and given a second chance to do so. Meanwhile, a Biden administration would likely try to codify the protection for Dreamers through legislation, and pursue further reform to offer a path to legal status for others living in the US without documentation.

Climate crisis

When it comes to action on climate change, Obama’s legacy was less tangible, and certainly more complex. The myriad layers involved in creating, executing and defending an agenda to combat the climate crisis made for inevitable problems to implement reform. This, combined with the heft of opposition, fake news and political baggage that accompanied the issue, made for a series of challenges, some victories and many disappointments for the Obama administration and those eager to embed a green government agenda during his two terms in office.