The Nastiest Election Fight In America Is Finally Coming To An End Tonight

After three weeks of mudslinging that followed a grueling primary campaign, what's been called the nastiest election fight in the U.S. will officially come to a close Tuesday night.

Mississippi voters are heading to the polls Tuesday to officially choose a Republican nominee for U.S. Senate. Incumbent Sen. Thad Cochran, who has held office since 1978, is hanging on for his political life against state Sen. Chris McDaniel, a Tea Party-aligned candidate who the GOP establishment worries could put deep-red Mississippi into play for moderate Democratic candidate and former U.S. Rep. Travis Childers.

Cochran, who lost a plurality of the votes in the early-June primary, is considered the clear underdog in the runoff. According to a Real Clear Politics average of three runoff polls, McDaniel enjoys a 6.3-point advantage heading into runoff day. In the most recent of those polls, conducted last Friday, McDaniel led Cochran by 8.

A source close to the Cochran campaign said they were "cautiously optimistic" despite the poll deficit.

"We have out worked them in this run-off. We'll see if it overcomes their rabid enthusiasm," the source said.

Typically, runoffs benefit insurgent candidates whose supporters are more likely to show up and vote a second time on an atypical election day. The most recent prominent example came in Texas in 2012, when current Sen. Ted Cruz (R-Texas) knocked off Texas Lt. Gov. David Dewhurst in a runoff.

However, the Mississippi primary has been unusual in a variety of ways. According to the Sunlight Foundation, spending on the Republican primary and runoff has exceeded $17 million, despite the fact Mississippi does not contain a single top-50 television market.

And voting patterns are shaping up to be another odd element of this race. According to Chism Strategies, requests for absentee ballots in the runoff election have increased 6% from the primary election, suggesting turnout will actually increase on Tuesday. According to multiple sources, such a phenomenon hasn't happened in a runoff election since at least 1984. Chism estimated turnout would increase about 10% from primary day, an unusual spike the firm said was "indication of more substantial field operations in the runoff."

The Cochran campaign has been working to bring non-traditional voters to the polls in an attempt to save his seat - including high-profile voter targeting of African-American voters who are mostly Democrats.

Outside groups supporting McDaniel have responded by sending poll watchers to election spots as part of "voter integrity projects." The McDaniel campaign warned on Tuesday that "liberal Democrats" were trying to decide who would be the Republican nominee.

However he gets there, increased turnout would benefit Cochran, who has stepped up his presence in the state after running what one Republican said was a "detached" primary campaign. The Cochran campaign has spent the last three weeks traversing the state, boasting of the federal money he's brought to the state and cautioning that a McDaniel tenure wouldn't be the same.

In one particularly scathing rant during a campaign stop, Cochran called McDaniel "an extremist" and "dangerous" because of some of his statements criticizing federal-spending levels

"He's an extremist. He said he wouldn't vote for disaster assistance for Mississippi. That is the most outrageous thing I've heard from a public official in Mississippi," Cochran said, according to a transcript provided by a spokesman.

It served as another moment of tension between the two campaigns in a race that has featured conspiracies, investigations, and arrests of people tied to both teams. The nastiness has continued to its final day.

On Monday, Cochran's daughter, Kate, posted a lengthy note to her Facebook page decrying what she described as her father's record being "snookered" by outside groups like the Club for Growth and Senate Conservatives Fund, which are both supporting McDaniel.

Here's an excerpt of her note:

I think this is the reason that so many seem swayed by my father's opponent: he is valued for his lack," she wrote. Lack of experience (he is not a "career politician.") Lack of wisdom (he relies solely on Jesus, the Constitution, and common sense* - combined in the veneer of 'goodness'). Lack of judgment (he vows to refuse federal monies and to try to impede legislation). Lack of specificity (what are 'Mississippi values'?). Lack of perspective (how does he believe for one moment that a junior Senator from the poorest state will have any influence in Washington? How can he believe that he will not want his family to live with him in the D.C. area?).

The McDaniel campaign seized on the "Jesus, the Constitution, and common sense" line, though Kate Cochran later clarified that she doesn't agree with McDaniel's version of common sense. The McDaniel campaign posted a photo of Kate Cochran with the quote, adding the curious hashtag, "#Who'sYaDaddy?" which, in turn, prompted a response from Cochran's campaign.

Said Cochran campaign spokesman Jordan Russell: "McDaniel's latest appalling attack on Sen. Cochran's family is further proof that he is unfit for office."

The attacks will come to an end tonight, one way or the other.