John Kasich, who has touted himself as the candidate of optimism in a darkly negative Republican presidential primary, went on the offensive against Donald Trump on Thursday and offered himself to the front runner's supporters as "a new vessel" to express their frustrations.
"He's not prepared to be president of the United States," Kasich said, citing a number of recent comments that Trump has made and then revised in recent days.
Notably among those were his controversial remarks to MSNBC's Chris Matthews that women should face punishment for seeking abortions if the procedure is outlawed. Hours later Trump issued a statement saying the doctors, not the women, should be held accountable.
"As a commander-in-chief and leader of the free world, you don't get do-overs. You need to get it right the first time," Kasich said.
The Ohio governor has attempted to stay out of what has been an increasingly nasty GOP primary. He has campaigned on a positive message and has gone out of his way to portray himself as a candidate who has stayed above the fray.
But, facing a significant delegate deficit to both Trump and Ted Cruz, his New York press conference Thursday showed a change in strategy, though his jabs at Trump were tepid compared to the personal attacks candidates have leveled against each other during the 2016 campaign.
Kasich, who has only won his home state, has slowly begun changing his tone and taking more aggressive shots at Trump. In a town hall with NBC News' Chuck Todd on Wednesday, he said he has not yet decided whether he would support Trump as the GOP nominee.
"I have two 16-year-old twin daughters. And if he happened to be the nominee, I would have to tell them why I would endorse him if I did," he said.
And as much as Thursday's event was aimed at undercutting Trump, it also was an appeal to his supporters.
"While the person that you have favored continues to move in an unmoored, untethered fashion, I understand that at times he is the vessel of your frustration," Kasich said in a direct appeal to Trump supporters. "And I want to offer myself up as a new vessel that can actually understand your problems, recognize your problems. And work aggressively to fix them."
There are not enough primaries left for Kasich to gain the 1,237 delegates needed to secure the GOP nomination, and his only path going forward will be dependent on picking up steam going into the Republican convention in July and winning a contested convention.
It's a possibility he is confident will happen. And delegates worried about what a Trump or Cruz ticket could do for down-ballot races, as well as Trump supporters who learn more about Kasich, will favor the two-term governor, he said.
"They see Coke, Pepsi and Kasich when they're shopping," Kasich said. "And they go, you know I kind of like the Kasich brand but I don't know much about it. So I might as well go with a Coke or a Pepsi. But what's happening now, I think, is people are getting more of a sense of who I am."
This article first appeared on NBCNews.com.