Jimmy Kimmel thinks Republican presidential candidate Nikki Haley is missing her best shot at defeating Donald Trump for the nomination.

Haley has pointed to Trump’s recent gaffes and stumbles as proof he’s not as sharp as he used to be. Trump fired back by challenging Haley to an “aptitude test,” and Kimmel earlier this week practically begged her to accept and take the test with Trump on live TV.

Instead, she challenged him to a debate.

“You are missing the point, Nikki,” Kimmel said. “He said he would crush you in a mental competency test. All you need to do is say ‘OK.’ No one wants to watch you debate him. We want to see him take this test.”

Kimmel envisioned Trump on television with a pencil “trying to figure out which one is a rectangle and which is a square.”

“That’s what we want, why is this so difficult to understand?” he said. “You wanna win, or you wanna finish second 54 more times in a row?”

And his advice didn’t end there.

See more in his Wednesday night monologue: