Missoula, Montana (CNN) A race for an open House seat in Montana took a jaw-dropping twist when a reporter alleged that Republican candidate Greg Gianforte "body slammed" him and broke his glasses on the eve of Election Day.

Late Wednesday night, the Gallatin County Sheriff's department charged Gianforte with misdemeanor assault.

The latest news came just ahead of an already much-anticipated special congressional election in the Big Sky state that pitted a folk-singing Democrat with a spotty financial past against a well-known Republican millionaire and businessman.

Republican Gianforte and Democrat Rob Quist face off Thursday to replace former Rep. Ryan Zinke, who President Donald Trump tapped to lead the Department of Interior. Before Wednesday night, Gianforte was viewed as the favorite in a fairly red state, where a Democrat hasn't held the congressional seat in two decades -- but the race is closer than many would have anticipated months ago, and the alleged physical encounter had many wondering if Gianforte might have changed the course of the race overnight.

Montana voters have surprised before. While the state overwhelmingly elected Trump by 20 points in November, they also have a populist streak and re-elected Democratic Gov. Steve Bullock over Gianforte just six months ago.

Here are six things to watch for tonight in the Montana special.

How much does the late allegation that Gianforte "body slammed" a reporter matter?

In Montana, any eligible voter can vote absentee. That means that a large number of votes in the Montana special election have already been cast. Any impact that Gianforte's alleged actions would have now would only impact the narrow slice of Montana voters who were planning to actually vote at the polls Thursday.

At a brewery in Missoula, where Quist held his final campaign rally, Democrats across the bar were speculating just how much the latest bombshell in the campaign saga would matter.

"It should make a difference," said Charley Carpenter, a Missoula resident and Quist supporter.

"The last thing we need is one more guy who flies off the handle," said Kate Gadbow, another Quist supporter.

But others argued that diehard Republican voters -- the base voters who are most likely to show up at the polls Thrusday and vote for Gianforte Thursday -- wouldn't be phased.

"I do feel like that side of the aisle, they don't care about stuff like that. ... If they're a Republican, they're going to give him a pass," said Democrat Dave Goodhart.

Following the event, the Gianforte campaign disputed the reporter's account.

"Tonight, as Greg was giving a separate interview in a private office, The Guardian's Ben Jacobs entered the office without permission, aggressively shoved a recorder in Greg's face, and began asking badgering questions," campaign spokesman Shane Scanlon said. "Jacobs was asked to leave. After asking Jacobs to lower the recorder, Jacobs declined. Greg then attempted to grab the phone that was pushed in his face. Jacobs grabbed Greg's wrist, and spun away from Greg, pushing them both to the ground. It's unfortunate that this aggressive behavior from a liberal journalist created this scene at our campaign volunteer BBQ," the campaign spokesman said in a released statement.

Assuming Gianforte wins, just how big is the margin of victory?

A Quist victory would be a major shock across the state and the country, but after a tumultuous few weeks for Trump, national Democrats are looking at Montana for any hint of Republican vulnerability. In the final weeks of the campaign, polls have tightened and even short of a surprise upset, a close call might indicate that Democrats -- with a retooled populist message -- are finding their footing again after stunning losses in 2016.

"I think Democrats have been pointing to a lot of special elections so far and arguing their turnout problems during Obama years are showing improvement now that Trump is president," said Kyle Kondik, a congressional campaign expert out of the University of Virginia's Center for Politics. "If Quist loses by 5 points, that is a pretty good showing."

Montana's special comes on the tail of two other special elections in Kansas and Georgia where Democrats outperformed expectations, but so far no Democrat has actually been able to clinch a victory.

Turnout, turnout, turnout

It's so key to what happens in Montana that it's almost become a cliché, but who turns out Thursday to vote is everything.

Special elections are notorious for lower voter participation. Add in the fact that the election is happening on a Thursday in May before Memorial Day and all signs point to a depressed electorate. Most would say a lower turnout would likely benefit Republicans, who tend to have a more reliable voting base, but the Democratic base across the country is fired up and you can't underestimate the fact that this is left-leaning Montanans first opportunity to register their frustration with Trump since he was elected. It's also impossible to predict how the latest alleged events might affect the race.

Many Montana voters will have already voted by that point with absentee ballots, but how the latest incident affects turnout is an unanswered question.

For Democrats, driving up turn out in Missoula County -- a Democratic stronghold -- and in areas where Native Americans make up a major chunk of the population including Big Horn, Glacier and Roosevelt County, will be key. Races in Montana can be won or lost for Democrats depending on how strong the turnout is on the state's seven reservations.

Republicans meanwhile will have their eyes on making sure their reliable, rural voters get out to the polls in dozens of places like Flathead, Ravalli and Beaverhead Counties. Drive-up turnout in the rural areas and the Gianforte campaign builds a firewall against a surprise Quist win.

Watch Yellowstone County

It's been called the Ohio of Montana. If you want to win in Montana, Yellowstone County -- the home of the state's largest city, Billings -- is an important place for Republicans to run up the score. On election night, Yellowstone County will give a strong indication of where the night is headed. Trailing far behind your opponent in the swing county is a bad sign.

In November, Trump won the county by roughly 27 points and went on to win the state by 20. Meanwhile, Gianforte won the county on election night in his race for governor, but only by roughly a point, a sign he was struggling to make up the margins he needed to beat incumbent Democrat Steve Bullock.

In order to pull out a surprise win in Montana, Quist would have to show early success in Yellowstone.

What impact do national money and surrogates have?

Montana is known for going against the grain in national elections, but that doesn't mean outside groups haven't tried to boost their candidates and influence the race.

On their own, Quist and Gianforte have raised $6 million and $4.6 million respectively with Quist bringing in a a late $1 million haul in the final week, according to his campaign. But that's just part of the story.

Republican-leaning outside groups have invested heavily in Montana's special. As of May 17, major campaign powerhouses like the National Republican Congressional Committee, the Republican National Committee and the Congressional Leadership Fund had spent more than $4.7 million in the race on Gianforte's behalf, according to an analysis by the Center for Responsive Politics. Likewise, the same analysis found that Quist had received a fraction of the help from Democratic outside groups who spent roughly $660,000

If Gianforte wins by just a hair, it may lead some progressives to ask why national Democrats didn't jump into the race sooner or more aggressively.

Outside surrogates have also played a big role in the campaign. Vice President Mike Pence and Trump's son Donald Trump Jr., a hunting enthusiast, stumped for Gianforte.

Over the weekend, Sen. Bernie Sanders, a progressive, made a last minute stop to rally voters across the state from Missoula to Billings for Quist.

A referendum on the Republican Health Care Law?

Any attempt to cast the Montana special election as a referendum on one piece of legislation passed hundreds of miles away should be taken with a grain of salt, but there is no denying Obamacare and the Republican attempt to repeal former President Barack Obama's signature law have been front and center in the Montana special.

Since the start of his campaign, Quist has taken the unusual step for a red-state Democrat and embraced the Affordable Care Act, even blaming a trail of unpaid taxes and debt on a botched gallbladder surgery he said left him financially strapped.

Gianforte, meanwhile, has been vocal about his desire to scrap the law and replace it with a Republican alternative. But Gianforte won't just take any replacement. The Republican has been reluctant to fully embrace the American Health Care Act that was passed narrowly out of the House of Representatives earlier this month, saying that he would have voted against the law.

Democrats have accused Gianforte of being dishonest about how he really feels about the AHCA after The New York Times revealed that on a fundraising call, Gianforte said that "the votes in the House are going to determine whether we get tax reform done, sounds like we just passed a health care thing, which I'm thankful for, sounds like we're starting to repeal and replace."

Depending on who wins, Democrats might learn valuable lessons for 2018 about how to script their position on health from the Montana special.