Republican presidential candidate Chris Christie said in a new ad that he was “wrong” to support former President Trump, now his rival for the GOP nomination, back in 2016.

“I have an admission to make: Eight years ago, when I decided to endorse Donald Trump for president, I did it because he was winning. And I did it because I thought I could make him a better candidate and a better president. Well, I was wrong. I made a mistake,” Christie tells the camera in the minute-long clip.

“And now, we’re confronted with the very same choice again,” Christie said, citing Trump’s lead in the polls.

Christie has become an outspoken Trump critic and pitched himself as the top Trump alternative in this year’s race, calling out the former president for not taking part in the party’s debates and sounding alarms about a second Trump term.

He said last week that Trump would “burn America to the ground.”

He’s also been firm in saying he wouldn’t pardon Trump if he were convicted of a crime, as the former president campaigns amid multiple legal battles.

But Christie has struggled to get closer to Trump in the polls, where Trump leads even his closest challengers by double-digits. 

The Hill/Decision Desk HQ polling average shows Christie at just 3.3 percent support nationally in the Republican primary, while Trump leads with 64.1 percent.

Still, Christie’s team has said it’s ready for the long haul, and the former New Jersey governor in the new ad dismissed calls for the GOP candidates trailing Trump to drop out of the race.  

“Donald Trump will sell the soul of this country,” Christie warned in the video.