Fresh from accepting the Republican nomination, US President Donald Trump had harsh words for anti-racism protesters on Friday during a campaign stop in the politically important state of New Hampshire. Addressing a crowd in an airport hangar, Mr Trump called the demonstrators who sought to disrupt his White House speech on Thursday night "thugs" and said Senator Rand Paul could have died when he was swarmed by protesters afterwards. Mr Paul said on Friday he was attacked by an "angry mob" of more than 100 people near the White House and had to be rescued by the police. "He'd either be in very bad shape, or dead, and that would include his wife, if those policemen didn't happen to be there," Mr Trump said of the Republican senator. The president has emphasised a "law and order" theme to motivate his political base and attract more voters as he trails former Vice President Joe Biden, the Democratic presidential nominee, in national polls ahead of the Nov. 3 election. "You know what I say? Protesters, your ass. I don't talk about my ass," he said. "They're not protesters. Those aren't protesters. Those are anarchists, they're agitators, they're rioters, they're looters." Mr Trump has been criticised for not showing empathy in the wake of shootings and killings of Black men by police, including George Floyd, who died in police custody in Minneapolis in May, sparking anti-racism demonstrations worldwide. New protests erupted in Kenosha, Wisconsin, this week after police officers shot Jacob Blake, another African-American man, multiple times in front of his children. He survived. Tens of thousands of protesters demanding an end to racial injustice and police brutality thronged the US capital on Friday, signalling a renewed groundswell of anger gripping the nation following a white officer's shooting of African-American Jacob Blake. Crowds flooded the National Mall for a mass march marking the anniversary of Reverend Martin Luther King Jr's historic "I have a dream" speech on August 28, 1963. Friday's demonstration was dubbed "Get Your Knee Off Our Necks," in reference to George Floyd, who suffocated beneath the knee of a white officer in Minneapolis in May, igniting the most widespread civil unrest in the country in decades. Al Sharpton, the civil rights activist who gave the eulogy at Floyd's funeral, told the crowd it was time for a "new conversation" with America. "We need to have a conversation about your racism, about your bigotry, about your hate, about how you would put your knee on our neck while we cry for our lives," he said. Often fighting back tears, relatives of Floyd, Blake and Breonna Taylor - a black 26-year-old shot dead by police in her own apartment last March - took turns addressing the sea of people, who repeatedly called out the victims' names in response. "Black America, I hold you accountable," said Blake's sister Letetra Widman. "You must stand, you must fight, but not with violence and chaos. With self love." Like his father 57 years ago, Martin Luther King III stood on the Lincoln Memorial steps and urged Americans to keep fighting inequality - and to vote in November at all costs to defeat President Donald Trump. "We are taking a step forward on America's rocky but righteous journey towards justice," King, at times wiping sweat from his brow, told a crowd enduring muggy Washington heat. MLK's granddaughter, 12-year-old Yolanda King, also spoke, telling the nation's youth they would "be the generation that dismantles systemic racism once and for all."