A defiant President Donald Trump accepted the Republican nomination for a second term on Thursday with a scathing attack on rival Joe Biden, asserting that a Democratic victory in November would only exacerbate the racial strife and coronavirus pandemic besieging the nation.

Speaking from the White House South Lawn despite criticism he was using the executive residence as a political prop, Trump portrayed Biden, a career politician with a long record as a moderate, as a far-left extremist who would usher in a lawless, dangerous America...