WASHINGTON • The United States may be focused the last few weeks on a domestic presidential campaign and the Middle East, but many foreign policy observers would agree that 2015 has been an encouraging year for United States President Barack Obama's Asia pivot.

Despite a preponderance of geopolitical distractions over the past 12 months, there were enough signs to demonstrate US commitment to the Asia-Pacific region.

At the top of the list is the completion of negotiations on the 12-nation free trade pact known as the Trans-Pacific Partnership (TPP).

Another important indicator of the importance of the Asia pivot was the amount of face time Asian leaders got in the White House. Last year, four heads of state of major Asian nations held summits with Mr Obama - President Xi Jinping of China, Prime Minister Shinzo Abe of Japan, President Park Geun Hye of South Korea and President Joko Widodo of Indonesia.

In fact, both ceremonial state dinners held in the White House last year were in honour of Asian leaders. Mr Abe attended as guest of honour in April while President Xi did the same in September. Not every meeting went smoothly, but the level of engagement was important nonetheless.

Militarily, the US also made significant moves to indicate its commitment to the region.

A move in October to send a guided missile destroyer on a freedom of navigation operation near two Chinese man-made islands in the South China Sea was America's strongest signal yet of its assertion that Beijing's aggressive land reclamation activities in disputed waters do not alter its sovereignty claims.

As bright a year as 2015 was for the US' Asia policy, there are few guarantees that the next 12 months will be as positive.

If past tenures are anything to go by, then we can expect Mr Obama to focus on foreign policy in the final year of his presidency. Yet, given the truly unpredictable nature of the current election campaign, it is difficult to say how domestic political pressures will ultimately influence his decisions.

To that end, we look at three themes from the US in 2015 that could affect US policy towards Asia - and South-east Asia in particular - this year.

U.S. SECURITY AND TERRORISM

Since the terror attacks in Paris in November and California last month, concerns about national security and terrorism have become the top issue on the minds of American voters.

At the start of November, a Gallup poll showed that just 3 per cent of Americans would cite terrorism as the most important US problem. At the top of the list was more traditional voter concerns like the economy (17 per cent) and government (15 per cent).

By the middle of last month, however, the list was turned on its head. The latest Gallup figures show that some 16 per cent of Americans now consider terrorism to be the country's biggest problem, statistics not seen since the London public transport bombings in 2007.

All this adds up to increasing pressure on Mr Obama to deal more decisively - or at least appear to deal more decisively - with the terror threat. That includes putting the terrorism issue and the battle against the Islamic State in Iraq and Syria (ISIS) front and centre - even if it is at the expense of other priorities.

An indicator of what lies ahead can be seen in the Republican response to the climate change agreement that came out of the Paris Summit last month. While much of the world heralded the deal, politicians in the US were slamming Mr Obama for focusing on the wrong issue.

"While the world is in turmoil and falling apart in so many different ways, especially with ISIS, our President is worried about global warming. What a ridiculous situation," wrote businessman and presidential candidate Donald Trump on Instagram, in a response echoed by many of his Republican colleagues.

It is thus going to be a stretch for the President to work on any priority - like lobbying Congress to ratify the TPP - while the situation in Syria and Iraq remains unstable. The juggling act that was achieved last year will be harder moving forward.

There is some overlap between its Asian policy and its terrorism priorities - Washington sees the potential involvement of moderate Muslim nations like Malaysia and Indonesia in its anti-ISIS coalition as a valuable symbol - but no one expects any kind of breakthrough this year.

Though both Jakarta and Kuala Lumpur have loudly condemned ISIS, they have chosen not to contribute to the coalition.

SOURING ON CHINA

Though it was a warm autumn day when Mr Obama and his Chinese counterpart, President Xi, stepped out into the Rose Garden for a joint press conference, there was an un-mistakeable sense of frost in the air.

And as the two leaders spoke, it soon became clear why. The much-hyped first state visit by Mr Xi would end with the US and China failing to narrow differences on anything that mattered.

An anticipated first-of-its-kind cyber arms deal was a damp squib, turning out to be a modest verbal proposal for the two governments not to support cyber criminals attacking the other, while the only thing said on the South China Sea issue was a reiteration of long-held positions.

With his Chinese counterpart beside him, Mr Obama did not even back away from an earlier threat to impose sanctions against Chinese entities engaging in cyber espionage.

The largely underwhelming summit - where the two sides seem more eager to prevent any further intensification of rivalry - captured the souring mood in the US for all things China.

After apparently trying a softer approach in 2014, the US administration reverted to a firmer one last year.

The two sides clashed multiple times throughout the year on cyber security. The disagreement on the South China Sea culminated with the US angering China by conducting a freedom of navigation operation and the Pentagon even released a National Military Strategy report that warned of a "low but growing" probability of war with a major power.

The tension between the two means South-east Asian countries may face an ever harder challenge trying not to get caught in between. Any agreement with one side - innocent or not - will inevitably be seen as leaning towards one power and away from the other.

Singapore got a small taste of that difficult tight-wire act last month. Despite statements from the Singapore authorities that a deployment of US P-8 Poseidon surveillance aircraft to Singapore was routine - and something the country has done for other militaries - the move was played up in Washington as an important step to shore up US operations in the South China Sea.

A DEEPENING POLARISATION

Finally, there is the matter of the increasing divide between the two political parties and the election that will give one the advantage.

Though Mr Obama's name is not on the ballot, as the incumbent, his policies certainly are. Republican candidates have promised to dismantle nearly every policy achievement of his if they win the White House. This includes repealing his landmark healthcare reform law and striking down his climate change initiatives and walking away from the Iran nuclear deal.

If the campaign thus far is anything to go by, then the Democrats and Republicans do not just disagree on the solutions, they often disagree on what the problems are in the first place.

While talk about climate change and income inequality has been a primary feature of Democratic debates, Republican ones have hardly touched on them. In the same way, Democrats have not spent nearly the same amount of time as Republicans talking about national security, tax simplifica-tion, immigration or religious liberty.

It is now difficult to even think of an issue that has any kind of overlap between both sides.

This problem is, of course, nothing new. A much-cited Pew study did a good job of quantifying the disappearing political centre. In 1994, the study found that 70 per cent of Democrats were more liberal than the median Republican and 64 per cent of Republicans more conservative than the median Democrat. By 2014, those numbers had become 94 per cent and 92 per cent respectively. And the problem is likely to only get worse.

Given that both sides now hold vastly different worldviews and foresee vastly different futures, the election this November could herald a radical change in domestic and foreign policy.

Asian governments will no doubt find a way to work with whoever takes the White House but, more so than ever before, who wins is going to make a difference.