Taking the stage for the first time since leaving office, former President Donald Trump on Sunday called for GOP unity, even as he exacerbated intraparty divisions by attacking fellow Republicans and promoting lies about the election in a speech that made clear he intends to remain a dominant political force.

President Donald Trump’s wild and unsupported claims of voter fraud have emerged as a high-stakes Republican loyalty test that illustrates the tug of war likely to define the future of the GOP whether he wins or loses the presidency.