The Ohio Senate race is heating up ahead of the state’s March 19 primary, with Democrats moving to boost President Trump’s pick in the state, Bernie Moreno, even as a late-breaking scandal roils the campaign.

In the final days of the GOP primary in the state, Democrats are looking to boost Mr. Moreno, painting him as “too conservative for Ohio” in a new $2.7 million ad campaign that links Mr. Moreno to Mr. Trump.

The Democrats’ ad buy is only the latest in a primary that has seen some $4.8 million spent on ads and another $142.7 million spent in pre-booking general election ads, according to a report by watchdog AdImpact.

Mr. Moreno is one of the biggest beneficiaries of spending, not just from Democrats but from Republican groups like Club for Growth Action and Buckeye Values, which have spent some $5.5 million and $1.3 million on supporting Mr. Moreno, respectively.

In a statement, a spokeswoman for the Democratic Senate Majority PAC, Hannah Menchoff, explained the ad about Mr. Moreno, saying that voters “deserve to know the truth about Bernie Moreno — and the truth is that Moreno is a MAGA extremist who embraced Donald Trump just like he embraced his policies to ban abortion nationwide and repeal the ACA.”

An Ohio state senator, Matt Dolan, one of Mr. Moreno’s chief rivals in the primary, is the only candidate with more ad support in the primary, with about $17.2 million being dedicated to backing his primary bid.

At the same time, Senator Brown, who is running for re-election in the increasingly Republican state, has had about $7.2 million spent supporting his candidacy, though Democratic groups backing his re-election have reserved some $65.6 million in as buys ahead of the general election.

The Democratic Moreno-boosting campaign comes as Mr. Moreno’s campaign is dealing with a scandal of its own after the Associated Press unearthed the existence of a 2008 profile on a site called Adult Friend Finder, seeking “Men for 1-on-1 sex.”

“Hi, looking for young guys to have fun with while traveling,” a caption on the profile under the username “nardo19672” reads.

While the Associated Press was able to confirm that someone with access to Mr. Moreno’s email created the photo-less profile, it was not able to definitively confirm it was Mr. Moreno himself.

When asked about the profile, a lawyer for Mr. Moreno’s campaign provided a statement from an intern who has donated to Mr. Moreno’s campaign, Dan Ricci, saying that the profile was “part of a juvenile prank.”

“I am thoroughly embarrassed by an aborted prank I pulled on my friend, and former boss, Bernie Moreno, nearly two decades ago,” Mr. Ricci said. The Associated Press notes it was unable to independently confirm Mr. Ricci’s claims.

Despite the budding drama at Mr. Moreno’s campaign, Mr. Trump, who is set to attend a rally in Ohio on Saturday, has redoubled his support for Mr. Moreno.

Even with Mr. Trump’s endorsement, it’s not clear that Mr. Moreno is the favorite to win the hotly contested GOP primary next week.

In a recent March 13 survey from Emerson College Polling and the Hill, Mr. Moreno was trailing Mr. Dolan by three points, 26 percent to 23 percent. Ohio’s secretary of state, Frank LaRose, polled in third with 16 percent support, and another 32 percent said they were unsure who they would vote for.

“Overall, Dolan is the third candidate to lead the Republican Primary ballot this year in Emerson polls: LaRose led in November, Moreno surged in January, and now Dolan has voters’ attention,” a pollster, Spencer Kimball, said in a memo accompanying the poll. “The shifting dynamics have left a significant number of voters undecided with less than a week until election day.”

In Emerson College’s general election polling in the race, Mr. Brown has consistently led each of the three Republicans vying for the nomination. The poll’s margin of error was plus or minus 2.6 points.