No one can afford to look weak. The latest American showdown with China was sparked by leaked plans for a possible visit by House Speaker Nancy Pelosi to Taiwan – and is particularly dangerous because it is driven by domestic politics on both sides of the Pacific. The spat is worsening already poor relations between the United States and China, as their 21st century superpower tussle takes shape. It also complicates a call expected as soon as Thursday between US President Joe Biden and Chinese leader Xi Jinping. Taiwan has long looked like the most likely spark to a military escalation between the US and China. Under the complicated web of agreements governing relations with Beijing, Washington only grants formal diplomatic recognition to the People’s Republic of China but maintains close ties with Taiwan – a self-governing democracy over which China claims sovereignty. The US’ policy of strategic ambiguity has left it hazy what it would do if China ever invades Taiwan, partly to avoid encouraging a formal independence declaration by the government in Taipei. But the US is bound by law to offer Taiwan the means to defend itself. China has vehemently warned that it will take “resolute and forceful” measures if Pelosi visits. An attack on her aircraft is unthinkable. But there is speculation in Washington that China might shadow her US military plane with fighter jets or even send aircraft flying over Taiwan itself – a highly volatile scenario fraught with the possibility for miscalculation. Given such rhetoric, it would be hard for China not to take unprecedented action if Pelosi did visit. Xi has little room to deescalate ahead of a national party congress later this year, which is expected to confirm his unusual third term. Biden, perhaps unwisely, revealed that the US military was not keen on Pelosi’s visit. Now, if he convinces the speaker not to go, he will be accused of caving to the Chinese, a charge that no US president can stomach – especially one whose approval rating has plunged below 40%. Pelosi, the third-highest ranking figure in the US government, has been sparring with China over human rights for 30 years and is not the type to be bullied. With Democrats tipped to lose the House in November’s midterm elections, she will be loath to make what could be one of her last big plays on the international stage a climbdown to Beijing. The White House, keen to avoid offending a Democratic icon and conscious of the political sensitivity of trying to strong-arm another branch of government, has been talking to Pelosi behind the scenes about the risks of her trip, according to CNN reporting. On Capitol Hill, hawkish advice is coming from both sides of the aisle. “We shouldn’t allow them to bluff and dictate to America, the greatest nation in the world, where our Speaker of the House should travel,” said progressive Democratic Rep. Ro Khanna of California on CNN’s “The Situation Room” Tuesday. “I mean, who are they to say that Speaker Pelosi shouldn’t go to Taiwan?” Republican Minority Leader Kevin McCarthy weighed in by saying that Pelosi “shouldn’t back down now.” He also said he would lead a congressional delegation to Taiwan if he becomes speaker next year – though such a visit would be potentially less explosive than one by Pelosi, since Biden could argue to the Chinese that rival Republicans do not represent his policy. Given the political tensions on both sides, it’s hard to see how Biden and Xi can ease the situation. Things could get dicey if Xi asks Biden to prevent Pelosi visiting. Biden has no power to make that happen. But the Chinese leader could take offense if the speaker then makes the trip, further fracturing trust. China, which is increasingly militarily capable, is also watching vocal bipartisan calls on Capitol Hill for strategic ambiguity to be ditched and for the US to simply state it would defend Taiwan. Biden hasn’t exactly helped by repeatedly making statements that walk all over the policy – only for them to be walked back by aides. Bonny Lin, the director of the China Power Project at the Center for Strategic and International Studies, said that the best that could come out of the call is perhaps some mutual understanding of exactly what China would do if Pelosi goes. “Hopefully, there is something the Chinese can give us in terms of understanding the way that China might respond so that the US and Taiwan can hopefully plan a way that will not create more escalation in this dynamic,” Lin said. But China may not yet know how it would respond, she added. And it may not be interested in steps that deescalate the situation. A lot is riding on what Pelosi decides to do.