TULSA, Okla. (Reuters) \u2013 US President Donald Trump\u00a0 told thousands of cheering supporters he had asked US officials to slow down testing for the novel coronavirus, calling it a \u201cdouble-edged sword\u201d that led to more cases being discovered. Trump said the United States had now tested 25 million people, far more than other countries. \u201cWhen you do testing to that extent, you\u2019re gonna find more people you\u2019re gonna find more cases. So I said to my people slow the testing down, please,\u201d Trump told a campaign rally in Tulsa, Oklahoma, where many supporters were not wearing face masks. A White House official said Trump was joking about his call for a slowdown in testing. \u201cHe was obviously kidding. We are leading the world in testing and have conducted 25 million + in testing,\u201d the official said. Trump said his actions in blocking travelers from China and Europe had helped save \u201chundreds of thousands of lives.\u201d But he said the \u201cradical fake news\u201d media had not given him credit for doing what he called \u201ca phenomenal job\u201d responding to the outbreak. In fact, several US states are reporting troubling spikes in coronavirus infection rates, mainly in the South and West, as Trump addressed America\u2019s largest indoor gathering in months. Health experts say expanded diagnostic testing accounts for some, but not all, of the growth in cases. They also call it a key tool in fighting the spread of the disease, which had been detected in at least 2.23 million people across the United States as of Saturday. COVID-19, the disease caused by the novel coronavirus, has killed more than 119,000 Americans to date, according to Reuters\u2019 running tally. A mounting volume of infections is elevating hospitalizations in some places. In his remarks, Trump used terms such as \u201cKung Flu\u201d virus and \u201cChinese virus\u201d to refer to COVID-19. \u201cThat name gets further and further away from China, as opposed to calling it the Chinese virus,\u201d he said. The US president initially dismissed the threat of the coronavirus, and sparred with state governors as they tried to slow its spread. His approval ratings have dropped in recent weeks, and Democratic presidential candidate Joe Biden now has a 13-point lead over Trump. Seventy-six percent of Americans remain concerned about the spread of COVID-19, according to the latest Reuters\/Ipsos poll.