Today’s the day that voters in South Carolina’s 1st Congressional District march to the polling stations and decide whether to elect the disgraced former governor or the comedian’s sister to represent them in the House of Representatives.  As if that wasn’t bad enough, now visitors will be coming to town to watch them make this embarrassing choice, and I don’t mean the media:

The Justice Department will monitor voting in Charleston County, South Carolina, in Tuesday’s special election to fill a House of Representatives seat, the department said on Monday.

Former South Carolina Republican Governor Mark Sanford is facing Democratic newcomer Elizabeth Colbert Busch, sister of television political satirist Stephen Colbert, in the First District House race.

The Justice Department said in a statement it was monitoring the election under provisions of the Voting Rights Act of 1965. The law bars election discrimination on the basis of race, color or membership in a minority language group.

Wait — did the DoJ get wind of some plot to steal the election?  (Given the choices, who would want to steal it?)  After all, the last time the DoJ decided to sit in on an election in this district was twelve years ago.  Why the sudden interest?

The department did not give a reason for the monitoring. Tuesday’s vote will take place under South Carolina’s new law mandating photo identification for voters, and Justice Department monitors observed primary elections.

Ah, right.  Attorney General Eric Holder opposed that law, and now appears to be trolling for anecdotes for his challenge to it.  Oddly enough, Holder didn’t appear too concerned about potential discriminatory conduct last November or in 2010 under then-existing law, when an African-American was on the ticket … for the Republican Party.  The DoJ apparently didn’t have enough concern to monitor those elections.

Trolling aside, the election today looks to be a nail-biter, even if neither side can take much satisfaction in having the winning candidate.  Politico offers five keys to watch in today’s election, but the real key is the second point:

There’s little doubt South Carolina Democrats are fired up about this race — volunteers have been pouring into Colbert Busch’s campaign offices, eager to elect one of their own in a Republican stronghold. Her supporters dominated the audience at a debate last week.

Colbert Busch needs all the enthusiasm she can muster, given the district’s conservative tilt; Mitt Romney won it by 18 percentage points.

“The Democratic base is energized in a way I’ve never seen before,” said Jaime Harrison, the South Carolina Democratic Party chairman. “We will have very strong Democratic turnout.”

Republicans, meanwhile, have to hope that their voters put aside their qualms with Sanford and head to the polls.

“Will [GOP turnout] be what we’ve seen in other elections or will it be depressed because they’re unhappy with Gov. Sanford and his past history?” said Republican state Sen. Tom Davis, a Sanford ally. “She has to hope for those who vote for Republicans not turning out.”

Turnout north of 28 percent would be seen as high — and a sign that Republican voters are heading to the polls despite their reservations about voting for Sanford. Anything lower than that would suggest Sanford is struggling and point to a good night for Colbert Busch.

Maybe the DoJ’s sudden presence will annoy enough Republicans to turn out, too.  Turnout is the only real clue that matters.  A higher Republican turnout will bury Colbert Busch no matter what happens in the other demos, and a low GOP turnout will bury Sanford similarly.  Sanford has a long history in this district — he won three House terms in SC-01 before becoming governor — and he knows how to turn out voters, as he proved in the primary.  Keep an eye on overall turnout.

Update: “Win or lose, Mark Sanford is having the time of his life,” says BuzzFeed’s Kate Nocera:

Driving, walking, and shaking hands with the formerly disgraced former governor through South Carolina’s first congressional district, it’s hard to remember that this was a guy whose national ambitions were shattered when he disappeared to Argentina for several days in 2009 to cheat on his then-wife.

Equally hard to remember is that when he entered the race there was a collective groan from Republicans across the state and in Washington D.C., who thought Sanford’s past was a liability that would put a safely Republican seat in Democratic hands for the first time in decades.

“The thought was it’s too early, you do a tour, you write a book, you do all those things to rehab your image and then you run,” said one former Sanford staffer. “But it turns out he’s crazy as a fox and it looks like he’s going to pull this off.”

We’ll see, but he’ll need that enthusiasm to extend to the act of voting, and not just showing up to watch the show.