Greg Gianforte just made a massive error on the final night of the Montana special election

(CNN)On the eve of Montana's special House election, Republican nominee Greg Gianforte got into a physical altercation with a reporter from The Guardian newspaper -- an incredibly odd and potentially damaging last-minute swerve in a race that has, of late, attracted considerable national attention and money.

In audio posted by the Guardian, reporter Ben Jacobs can be heard asking Gianforte a question about health care -- in the wake of the Congressional Budget Office's analysis released Wednesday afternoon. Gianforte deflects the question. Jacobs asks again, insistently but, at least by my ears, politely. A scuffle can be heard and then a crash.
"Sick and tired of you guys," Gianforte can be heard saying. "Get the hell out of here." Jacobs responds: "You just body-slammed me and broke my glasses."
Gianforte spokesman Shane Scanlon offered his own version of events in a statement released just before 9 p.m. eastern.
    "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," 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 police were called to the scene, and Jacobs told MSNBC's Chris Hayes that "I'm going to get my elbow checked out." Buzzfeed's Alexis Levinson, who was also at the event, tweeted that "Gallatin County Sherriffs now taking witness statements."
    Levinson added: "(Gianforte) is leaving the event without speaking. I asked his aide what (was) going on and (they) wouldn't answer."
    Gianforte has been charged with misdemeanor assault in relation to the incident. He's received a citation and is scheduled to appear in Gallatin County Justice Court between now and June 7, the sheriff's office said.
    It's not entirely clear what the effect of the Gianforte incident will be on the election tomorrow. Montana allows voting by mail and, as of Tuesday, more than 250,000 ballots had been returned, according to Michael McDonald, an associate professor at the University of Florida. (Here's a link to the Montana Secretary of State's site.)
    How many votes remain to be cast -- and how many of those voters are truly undecided and might be swayed by an episode like this -- remains to be seen. And, because so many of the details are unclear at the moment, it's not at all certain how the story even turns out over the next 24 hours.
    But I will say that the audio released by the Guardian seems damning for Gianforte. And it doesn't jibe, at all, with the statement released by the campaign.
    If Gianforte did, as Jacobs alleges, body slam a reporter, it follows on two other recent incidents in which reporters were roughed up for asking questions of public figures. In West Virginia, a reporter was arrested when he approached Health and Human Services Secretary Tom Price and began asking questions. Then, earlier this month in Washington, a reporter was pinned against a wall by security guards at the Federal Communications Commission when he approached FCC Commissioner Michael O'Rielly.
    This latest controversy couldn't have come at a worse time for Republicans. Polling has shown the Montana special election narrowing in the race's final days, despite the fact that President Donald Trump carried the "Last Best Place" by 20 points in 2016. Republicans, already on edge about the possibility of a wave forming that might endanger their House majority in 2018, view a win in Montana as a way to settle their nerves and push back against the negative national narrative -- particularly with the special election in Georgia's 6th District next month looking like a dicier proposition for the party.
    The allegations against Gianforte complicate what was already a tighter-than-expected race. And are just more bad news for a Republican Party that has dealt with a whole lot of it of late.