Florida Governor Ron DeSantis worked hard in the first full week of his 2024 presidential campaign to establish himself as a contender to voters — and just as hard to characterize the man who stands in his way for the Republican nomination.

DeSantis, 44, made his case for being the more conservative and consistent alternative to Donald Trump, the former president and current front-runner in the campaign, as he toured 12 communities in three early-voting states.

Trump fired back in a sudden escalation of the war of words between the two men that not only heightened tensions in the Republican race but also provided insight into DeSantis’ initial strategy.

Touring Iowa, New Hampshire and South Carolina this week, the governor continued to cast himself as an unapologetic warrior on issues such as abortion, immigration, government spending, crime and LGBTQ rights.

But for the first time, DeSantis began to draw sharp contrasts with Trump, painting the former president as a politician who had lost his way and who became a creature of the government he was supposed to transform by compromising too readily.

Trump’s camp has tried to do the same to DeSantis, calling him a “swamp puppet” and playing down his accomplishments as Florida’s governor. In a party where being a political outsider still holds broad appeal, neither wants to be tagged as the candidate of the establishment.

“That’s why they’re doing it,” said David Kochel, a veteran Republican presidential campaign operative in Iowa. “It’s a dirty word.”

DeSantis’ tour of the three states that will hold the first nominating contests of the Republican primary next year was aimed at quickly cementing himself as Trump’s largest threat.

He largely played to small but packed venues and supportive crowds, even if several voters told Reuters they had not decided on who to vote for.

In speeches, DeSantis notably did not criticize Trump by name, but instead made more opaque references, telling audiences that he would be the candidate to “finally” secure the U.S. southern border or that “leadership” was more important than “building a brand.”

It was a way of nodding to Trump’s supporters that he would continue his work without antagonizing them by insulting the former president, who still has many fiercely loyal supporters.

But in speaking to the media, DeSantis was less guarded. He suggested Trump, his main rival for the nomination had moved “left” during his White House term and that he was no longer the same candidate that ran in 2016.

DeSantis called Trump’s penchant for giving his opponents nicknames “petty” and “juvenile,” in an interview with a New Hampshire radio station on Thursday.

“I don’t think that’s what voters wants and honestly, I think his conduct, which has been doing for years now, I think that’s one of the reasons he’s not in the White House now,” DeSantis said.

DeSantis contrasted Trump’s time in office with his own as Florida governor, where he and the Republican legislature have enacted a long string of conservative reforms.

“There’s always going to be ways you can say you can’t do something,” DeSantis told a crowd in Gilbert, South Carolina on Friday as he wound up his tour. “There will always be easy excuses that you can proffer.”

Trump dominates the Republican field with 49% support, while DeSantis is next with 19%, according to the latest Reuters/Ipsos opinion poll conducted in May.