WASHINGTON — Republicans opened their prime-time convention Monday night with dark warnings about America’s future if President Donald Trump fails to win a second term, casting him as a protector of religious freedom, the nation’s workers and much more.

A school teacher warned that conservative values were under attack from labor unions. A small-business owner charged that businesses across America were facing unwarranted pandemic shutdowns and riotous mobs. And Rep. Matt Gaetz, R-Fla., likened the prospect of Democrat Joe Biden’s election to a horror movie.

“They’ll disarm you, empty the prisons, lock you in your home, and invite MS-13 to live next door,” Gaetz declared.

Trump, who was not scheduled to deliver his keynote convention address until later in the week, made multiple public appearances throughout the first day of the four-day convention. And while the evening programming was carefully scripted, Trump was not.

“The only way they can take this election away from us is if this is a rigged election,” Trump told hundreds of Republican delegates gathered in North Carolina, raising anew his unsupported concerns about Americans’ expected reliance on mail voting during the pandemic. Experts say mail voting has proved remarkably secure.

The GOP convention marks a crucial moment for Trump, a first-term Republican president tasked with reshaping a campaign he is losing by all accounts, at least for now.

A deep sense of pessimism has settled over the electorate 10 weeks before Election Day. Just 23 percent of Americans think the country is heading in the right direction, according to a new poll from The Associated Press-NORC Center for Public Affairs Research.

The evening program highlighted the tension within Trump’s Republican Party. His harsh attacks against Democrats who are trying to expand mail voting and demonstrators protesting deaths in police custody, for example, often delight his die-hard loyalists. Yet the party pointed to a somewhat more diverse convention lineup with a more inclusive message designed to expand Trump’s political coalition beyond his white, working-class base.

Two of the three final speakers on the prime-time program were people of color: former U.S. ambassador to the United Nations Nikki Haley and South Carolina Sen. Tim Scott, the only Black Republican in the Senate.

And one of several African Americans on the schedule, former football star Herschel Walker, defended the president against those who call him a racist.

“It hurts my soul to hear the terrible names that people call Donald,” Walker said of his friend.