It all starts with who knows the Chinese President Xi the best.
Trump has called the most powerful Chinese leader since Mao Zedong on Friday as he probed for
"Sleepy Joe: He's a pretty sleepy guy. He's not going to be able to deal with President X." Trump told reporters.
But his attack may be a backfire – because the former vice president knows Xi as Well, if not better, than Trump does.
He was tasked with Obama administration with courting then-Vice President Xi during his apprenticeship for China's top job.
"I've spent so much time with Xi Jinping as anybody has, "Biden boasted on the midt erm election trail ̵
"When he went to Muscatine, Iowa, I told him I could not go – but I should have gone. He went and he became the president. I did not go and I'm still the vice president, "Biden quipped at another State Department reception for Xi – who was by then Chinese President – in 2015.
Historic shift in US-China relations
With their buddy boasts about Xi, Biden and Trump may be offering a taste of a testosterone heavy general election race should the veteran Democrat win the nomination.
But the banter underscores the new political signif
Whoever eventually emerges as Trump's Democratic opponent will have no choice but to have a robust Chinese policy to compete with the President's own aggressive approach.
For years, the goal of US policy was to manage China's entry into the global economy. the hope of heading off a hegemonic confrontation between Washington and Beijing.
Under Xi, China has been acting with increasing self-confidence in Asia, building up its military and spreading its economic and diplomatic wings in Europe and Africa.  US efforts to frame a competing US-friendly regional trade and regulatory network were hampered by Trump's decision to exit the Trans-Pacific Partnership Pact soo n after taking office.
In its new National Security Strategy document, the Trump administration is branded China, along with Russia as a "revisionist" power that uses "technology, propaganda and coercion to shape the world antithetical to our interests and values.
The 'King' of China
Trump's approach to China has been mercurial
On the campaign trail, he slammed China for "raping" US workers and blasted previous Presidents as soft
In office, Trump has escalated tensions by slapping $ 250 billion in tariffs on Chinese goods, drawing reprisals from Beijing. The two powers have been on the verge of a trade war for months.
Yet, Trump has been personally bonded with Xi, drawn to strongman qualities that have seen him melt in the company of autocrats such as Russia's Vladimir Putin and North Korea's Kim Jong Un.
"He said," But I am not king, I am the president. ' I said 'No, you're president for life, and therefore you're king,' 'Trump said. "He said, huh. He likes that. I get along with him great."
The test for Trump is whether that person relationship can deliver something tangible for the United States.
Trump is not the first President to complain
But if he can forge a breakthrough with China on these issues, he could deliver a significant diplomatic achievement that alienated his predecessors.
Many in the The US business community, however, is expecting a more limited agreement – perhaps including large Chinese purchases of US goods to narrow the trade gap – that Trump will cry as historic nevertheless.
A significant number of prominent Democrats and legislators back to Trump's populist approach to trade with China – one of the ways in which the Democratic Party politics have changed since Biden left office.
Biden may have no choice but to adopt a similar duality to Trump in rel ations with Xi – is, on the one hand, touting his close relationship with Asia's most powerful man while at the same time adopting a strong set of policies designed to counteract Chinese action on trade, human rights and territorial disputes with US allies in the South China Sea
But neither Trump nor Biden doubt the stakes.
"The history of the next 50 years is going to be largely based on how well our two countries, the United States and China, navigate this relationship," Biden said Xi in 2015.
Trump told Xi in the Great Hall of the People in Beijing in 2017 that "a great responsibility has been placed on our shoulders."