Neal Dunn under fire as some Republicans attempt to clear the field in fight to face Gwen Graham in 2016

Panama City Republican Neal Dunn has filed for Florida’s 2nd Congressional District, ensuring there will a GOP primary in 2016.

Dunn is the Panhandle urologist who will face newcomer Mary Thomas, the general counsel for Gov. Rick Scott’s Department of Elder Affairs, in next year’s Republican primary.

The winner will seek to unseat incumbent U.S. Rep. Gwen Graham, a first-term Democrat.

Dunn’s entry on the race is the latest move by North Florida Republicans battling for the title of “most conservative,” in what could become a long, combative campaign.

Even before filing, Dunn was under attack by opponents for being a RINO:  Republican in Name Only.

A longtime Bay County Republican and former Steve Southerland supporter, Dunn had been appointed by state Sen. Don Gaetz in 2014 to the Enterprise Florida Board of Directors.

Nevertheless, what raises the ire of a handful of North Florida conservatives was a donation from Dunn to Charlie Crist, the former Republican governor running against Tea Party favorite Marco Rubio for the U.S. Senate in 2010.

Although the $1,000 donation, made in September 2009, it was months before Crist switched from Republican to run as an independent, Crist later became a Democrat to run governor in 2014.

Crist’s party switch rankled many in the Florida GOP, and is widely credited for his narrow loss to Scott — a largely unpopular governor — last year.

Among other concerns are donations Dunn made in 2005 and 2006 to Democratic Rep. Allen Boyd, as well as money to U.S. Sen. Bill Nelson in the race against Connie Mack in 2012.

Dunn campaign spokesperson Marc Reichelderfer dismisses the accusations as “absolutely false.”

In am email to Florida Politics, Reichelderfer said that in the last 20 years, Dunn, in his own name, contributed more than $58,000 to Republican candidates and the Republican Party.

“To single out a few other contributions to try and use as an indictment against Dr. Dunn’s Republican credentials is completely disingenuous,” he added.

Another claim by opponents attempts to put the newly minted candidate at odds with fiscal conservatives. As Florida Politics reported, the claim was that state financial disclosures show Dunn owing more than his net worth.

Dunn’s campaign also says that assertion is false.

Reichelderfer points to Form 1 Statement of Financial Disclosure, required by the state of Florida as part of Dunn’s nomination to the Enterprise Florida post. Form 1, which asks for sources of income, does not specify any dollar figures, net worth or outstanding loan balances.

Reichelderfer says these accusations are simply mudslinging against a fellow Republican, and is unfortunate so early in the campaign.

If Dunn’s GOP opponents are going to attack, he said, they had “better get (their) facts straight.”