CLEVELAND — Donald Trump endorsed Bernie Moreno in December, catapulting the businessman to contention in an Ohio Senate primary featuring two better-known Republicans.

But with less than two weeks until the primary, the race has turned increasingly hostile as it remains in a competitive haze.  

There have been few independent polls to measure the three candidates running for the chance to unseat Democrat Sherrod Brown in what is expected to be one of the top Senate battles this fall. One internal poll from the Moreno campaign last week showed him with a double-digit lead over Ohio Secretary of State Frank LaRose and state Sen. Matt Dolan, but it also found roughly a quarter of likely primary voters remained undecided. Other close observers believe the primary is much tighter.

“From everything I’ve seen in both public and private polls, along with talking to folks on the ground, the Senate race looks like it’s a dead heat,” said GOP strategist Scott Guthrie, a veteran of Ohio Senate campaigns who is not aligned with any candidate here this cycle. “I’ve seen polls with each of the candidates in the lead, and everyone is within the margin of error.” 

The three candidates are set to meet for their final debate Wednesday. And while a rally with Trump could help push Moreno across the finish line, a source close to the former president told NBC News that an Ohio visit is “highly unlikely” before the March 19 primary but declined to elaborate.

The vitriol in recent days has approached the level of the unrestrained nastiness seen in the state’s 2022 Republican Senate primary, won by JD Vance after a game-changing endorsement from Trump. Operatives supporting LaRose and Dolan view aggressive attacks from Moreno and his allies, as well as other developments, as evidence of a wide-open contest this year in which the Trump-backed candidate is having a tougher time making his case.

A new ad from Moreno brands both Dolan and LaRose as anti-Trump clones of Nikki Haley in a state where devotion to the former president runs deep. Moreno’s allies at the Club for Growth are on air attacking Dolan for a gas tax increase that he — and many other Republicans in the Ohio Legislature — supported five years ago. 

Meanwhile, the pro-LaRose Leadership for Ohio received a late cash infusion that strategist Joel Riter said will keep the super PAC on the air through the primary. The group’s new ad includes footage from a 2019 interview in which Moreno questioned whether “you really need 100 bullets” in your gun. Moreno, who has moved to the right on several issues as he seeks elected office, now frames himself as an ardent supporter of gun rights.

“If Bernie and his team thought they were really up 10 points, I think they would have taken a much different tack the last few days,” LaRose spokesperson Rich Gorka said. 

“It’s up to the candidate to close,” Gorka added, noting Moreno’s experience as a car dealer. “I know he was a good car salesman, but he’s obviously not closing with voters.”

Dolan strategist Chris Maloney took a similar swipe at Moreno. 

“Inside of two weeks, his image is cratering, and his attacks don’t correlate with his inflated poll numbers,” Maloney said. “He should go back to selling cars because he’s proven incapable of selling himself.”

Asked how Moreno viewed the race, spokesperson Reagan McCarthy described it as a fight against the “RINO establishment” — using the acronym for “Republican in name only” — while emphasizing endorsements from Trump, Vance and Rep. Jim Jordan, R-Ohio.

“If the Dolan and LaRose campaigns think they can continue smearing us with left-wing media lies, without us responding, they’re mistaken,” McCarthy said. “Ohioans are sick of RINO career politicians like LaRose and Dolan and want to send another political outsider and businessman to the U.S. Senate who will stand with President Trump, Sen. Vance and Congressman Jordan.”

Sniping among the candidates’ advisers and allies has grown especially vicious since last weekend. 

When Vance on Saturday threatened on X to withhold support for legislation or projects championed by those “fighting Trump and his endorsed candidates,” without naming names, LaRose responded by highlighting Moreno’s past more-moderate views on gun control. Vance, whose friendship with LaRose has deteriorated over the course of the primary, fired back by calling attention to the secretary of state’s past support from LinkedIn co-founder Reid Hoffman, a top Democratic donor.

Gorka then mocked Vance for the “readers context” flag — “Vance has publicly called Trump an ‘idiot,’ ‘reprehensible’ and ‘noxious’” — added to his initial X post. Donald Trump Jr. and several Trump allies popular with the right online jumped into the social media fray, too. The former president’s son keyed in on LaRose’s work with No Labels, the centrist group seeking alternatives to Trump and President Joe Biden. (The next day, a top No Labels official urged support for LaRose in an email first reported by NBC News.)

“We’ve definitely touched a nerve in the Moreno campaign,” Gorka said. “And I think that what you’re seeing is exactly that. This is a very tight race.”

Jai Chabria, a Vance adviser who steered the senator’s successful 2022 campaign and has advised LaRose in the past but is neutral in this year’s Senate race, found the attacks counterproductive.

“It’s incredibly stupid for operatives to attack a popular conservative U.S. senator in a Republican primary rather than their opponent,” Chabria said, referring to Vance. “They are lucky you don’t need a license to do this work, because it would be revoked.” 

The campaigns and other Republican groups had spent nearly $24 million on advertising through Tuesday, according to AdImpact, an ad tracking firm. 

Dolan led the way, with $8.1 million in ads, followed by Moreno at $6.5 million. Both are heavily self-funding their campaigns, while LaRose is relying on the allied Leadership for Ohio PAC, which spent $4.3 million through Tuesday and reserved another $1 million through the primary. The Moreno-aligned Club for Growth, which has begun attacking Dolan, spent $2.2 million and booked $2.8 million more.

Gorka and Maloney said they believe that ads focused on Moreno’s policy flip-flops and local news coverage of lawsuits filed against his businesses have helped keep the race close, despite Trump’s endorsement. Both also touted robust ground games and rigorous schedules. LaRose has held more than 30 events over the last two weeks, Dolan more than 25. Dolan’s campaign also has made more than 300,000 voter contacts through phone calls and visits to homes since Jan. 1, Maloney said. Moreno’s campaign, meanwhile, emphasized 70 events over two months and endorsements from nearly a dozen county GOP groups.

“There will be a lot of ads and dollars flying around in the final two weeks,” Guthrie said. “But at this point I think it’s anyone’s game.”