Political commentator Ann Coulter labeled Ted Cruz "a little bitch" Thursday, after the senator refused to endorse GOP nominee Donald Trump at the Republican National Convention.

On CNBC, she said other candidates like Marco Rubio were able to endorse Trump, while Cruz clearly isn't able to deal with losing the Republican nomination.

"Rubio comes out and, tepid as it may be, he does endorse Donald Trump," Coulter said. "It's Cruz who is a little bitch who can't get over it."

Coulter said Cruz likely "committed [career] suicide" when he told conservatives to vote their conscience instead of outright endorsing the GOP nominee.

"I'm beginning to understand why Ted Cruz has been hated by everyone every place he's ever been, from kindergarten to the United States Senate," she said.

"I must tell you, the only way I'm making money this year is on bar bets trying to get Donald Trump in the White House," she added. "I would have lost if we had made a bet on who would endorse Donald Trump first: Marco Rubio or Ted Cruz."

Rubio, she explained, is basically the standard bearer for the so-called "establishment," which is "very much against having borders in our country." But she said Cruz should have been more forgiving to Trump.

"You would think it would occur to him, 'Every place I've ever been, everyone has hated me. My only shot is to tie my wagon to Donald Trump. Maybe I can be attorney general or solicitor general,'" Coulter said.

Coulter has been one of Trump's loudest and most enthusiastic supporters since the billionaire businessman first announced his White House bid in June 2015.