A moderate Republican who represents a swing Staten Island district, Grimm has been atop Democratic target lists for months. National Democratic strategists have been talking up the idea of spending hundreds of thousands of dollars to unseat the second-term congressman. They want to hit the airwaves with TV ads casting him as a tea party figure who’s too conservative for his district.

Grimm’s altercation with a reporter who asked the congressman about a federal investigation of his campaign finances instantly went viral – footage played in an endless loop on cable TV and garnered hundreds of thousands of hits on YouTube.

( WATCH: Grimm presser after altercation)

“I’ll break you in half. Like a boy,” the former Marine and FBI agent told the NY1 cable TV reporter Michael Scotto.

Some Republicans worried that the memorable images would provide Democrats with more fodder for attacks this fall.

“It’s going to have an impact on the race…He’s been very angry and very aggressive. It’s the State of the Union. It’s a solemn event,” said Leticia Remauro, a former Staten Island Republican Party chairwoman. “People are going to ask, ‘What’s going on here?’”

Domenic Recchia, a New York City Councilman and Grimm’s Democratic opponent, wasted no time seizing on the incident. In a fundraising appeal to supporters Wednesday afternoon, he wrote: “We shouldn’t have a Congressman who resorts to bullying, threats and even more extreme tactics to get what he wants. … It’s time for Michael Grimm to go. He continues to be an embarrassment to his district and to his constituents.”

Not everyone agrees that the incident will seriously undermine the congressman’s reelection bid. Coming nearly nine months ahead of the election, they argue, few voters will remember it by the time they head to the polls. And some Republicans say Grimm’s tough-guy image could be an asset in a New York City district where voters are more likely to reward brashness.

“I don’t think [voters] would take a lot of umbrage over him roughing it up with a reporter a little bit,” said David Catalfamo, a former top aide to onetime GOP Gov. George Pataki.

It’s not the first time Grimm’s personal behavior has come under the microscope. The congressman has been dogged by an investigation into fundraising practices he employed during his 2010 campaign, with officials looking into whether he evaded donor limits. And in 2011, The New Yorker published an article reporting that Grimm had been investigated internally at the FBI over whether whether he used excessive force during an undercover operation.

Despite those bruises, Grimm managed to easily win reelection in 2012. Overcoming the moderate tilt of his district – which President Barack Obama carried that year – the congressman received 52 percent of the vote, prevailing over a relatively weak Democratic opponent. In his first race for the seat two years earlier, Grimm, boosted by endorsements from former Alaska Gov. Sarah Palin and former New York City Mayor Rudy Giuliani, won a hard-fought Republican primary and then notched a narrow win over then-Democratic Rep. Michael McMahon.

Grimm began his reelection race as the favorite. Some handicappers see Recchia as a flawed opponent because he hails from Brooklyn and the district is centered on Staten Island. Plus, without Obama running at the top of the ticket in 2014, there’s a possibility that fewer Democratic voters will turnout.

On Wednesday morning, Grimm issued an apology to the reporter and announced that he’d be going out to lunch with him next week. But some Republicans called Grimm’s dust-up an unforced, made-for-the-tabloids mistake that’s likely to come up repeatedly as the election year unfolds.

“It doesn’t help,” said O’Brien Murray, a Republican strategist in New York City. “The question is how much it hurts him.”