Xi Jinping, Marjorie Taylor Greene.

President Joe Biden went to the State Department on Thursday to reaffirm his commitment to diplomacy and US alliances, after a Trump presidency that disdained both and gutted the foreign service. Biden knows those alliances, in Europe and Asia, will be key to coping with a rising China. Xi Jinping has made clear his intent to surpass the United States as the world’s dominant economic and technological power, and to shape a new global order that revolves around Beijing’s authoritarian model. Donald Trump’s erratic, America First, get-tough efforts failed to curb Xi’s ambitions.

Yet, across town at the Capitol, the rhetoric of Marjorie Taylor Greene laid bare Biden’s biggest challenge to managing the competition with China: the global perception that US politics are consumed by crazy conspiracy theories that are dragging the country down. Chinese Communist Party communiques and media are filled with triumphalist conviction that China is historically destined to rise as the United States falls. US allies worry they have to hedge their bets with China.

So the biggest China policy question is whether Biden can, as he put it, “reclaim our credibility” as a global leader. The stakes are immensely high.

The China challenge is not a repeat of the Cold War with the Soviet Union. After World War II, the United States engaged in a policy of “containment” with the Kremlin, based on US diplomat George Kennan’s famous 1946 “long telegram,” which argued that the Soviet Union would ultimately collapse because of internal contradictions. But as the Financial Times’ chief economics commentator, Martin Wolf, argues, “Containing China is not a feasible option.” The Soviet Union’s rigid, state-controlled economy failed to adapt and grow, whereas China has made stunning economic and technological advances over the last four decades. Wolf estimates China’s economy “could be as big as those of the US and EU, together” by 2050.

And China is so integrated into the world economy — again unlike the Soviet Union — that even as the United States tries to untangle supply chains from China dependence — most countries want good relations with both Washington and Beijing. Even the Europeans have trouble resisting Chinese lures. The EU just signed on to a massive Chinese investment deal, rejecting Biden’s request to wait until he was inaugurated and could discuss it with them.

All this matters, because Xi Jinping has exhibited a ruthlessness, and willingness to crush dissent not seen since Mao Zedong, whom he seeks to emulate. On a visit to Beijing, in late 2019, I visited China’s National Museum on Tiananmen Square, where one wing contains the whole sweep of modern Chinese history from the mid-1800s to Xi’s predecessor, Hu Jintao. The second wing is dedicated solely, complete with videos and an enormous mock-up of Chinese military maneuvers, to all the glorious achievements of Xi Jinping.

So Biden’s intent to rejuvenate alliances in Asia, and Europe as well, is crucial to making Xi take notice that if he oversteps certain lines, democratic nations will push back.

Yet our allies don’t know whether they can still trust American leadership. As Wolf writes: “Over the last two decades and especially the last four years, the US has devastated its reputation for good sense, decency, reliability and even adherence to basic democratic norms.” (And the US reputation for competence has been smashed this past year by Trump’s dismal failures in dealing with COVID-19.)

And how can allies be certain Trumpism won’t return to the White House in four years?

To deal with China, Biden will have to convince allies — and Beijing — that the United States can get its own house in order. It will be tragic if GOP leaders undercut the crucial effort to counter Xi Jinping.