Nevada Republicans canceled their presidential preference vote and are giving Trump all their convention delegates.
The Democratic presidential candidate joked about the possible option during a town hall in Reno, Nevada.
Former Massachusetts Gov. Bill Weld is hoping to win enough delegates in the primaries to have a say – and maybe make a stink – at the summer convention.
The president has the support of nearly 90% of the state’s Republicans.
Former Massachusetts Gov. Bill Weld is left fighting Trump after former Illinois congressman Joe Walsh dropped out.
"We know that he wants reporters to roam free in Iran,” GOP presidential challenger Bill Weld said. But in America, "he says a free press is the enemy of the people."
Trump's 2020 Republican challenger did not name names.
South Carolina is among at least four states that have nixed Republican primaries and caucuses, an effort that helps smooth Trump’s path to reelection.
The president's GOP rival said Trump's phone call with Ukraine goes beyond "undermining democratic institutions."
"Warriors stand and fight for what they believe," wrote three of the president's Republican challengers.