The South Carolina Senate runoff between Rep. Jim DeMint (R) and former Gov. David Beasley (R) will be decided today, the most high-profile race on the ballot nationwide.

Elsewhere, Republican voters in Utah will decide two primary fights — in the 2nd and 3rd districts.

The South Carolina race has garnered significant national attention, as it is seen as one of Senate Republicans’ best chances to take over a Democratic-held seat this year.

Beasley and DeMint emerged from a six-way Republican primary on June 8 with 37 percent and 26 percent, respectively.

DeMint quickly wrapped up the endorsement of real estate developer Thomas Ravenel, who finished a close third in the primary, and seems to have the momentum heading into Election Day.

The two key battlegrounds, both campaigns agree, are the Upstate, which encompasses the northern reaches of the state, and the Lowcountry, anchored in Charleston.

Those areas, while both reliably Republican, have very distinct voter profiles.

The Upstate is generally seen as the home of movement conservatives who put social issues at the top of their voting concerns.

The Lowcountry is more well-to-do, populated by moderate, so-called “country-club” Republicans.

The Upstate is DeMint’s political base — he represented the Greenville area for the past six years in Congress.

He did not do as well as expected there in the primary, however, as Beasley narrowly edged him out.

The Lowcountry, where neither candidate has a political base, has tipped decidedly to DeMint as his campaign has touted the endorsement of Ravenel, a popular figure in Charleston.

The winner of today’s runoff will face state Superintendent of Education Inez Tenenbaum (D) this November in the race to replace retiring Sen. Fritz Hollings (D). Both national parties are expected to invest heavily in the contest.

In Utah, meanwhile, Republicans Tim Bridgewater and John Swallow appeared to be in a statistical dead heat on the eve of today’s 2nd district primary.

A poll concluded Thursday found Swallow, a former state lawmaker and the 2002 nominee against Rep. Jim Matheson (D), leading Bridgewater, a venture capitalist, 29 percent to 24 percent, which was within the poll’s margin of error.

The two have been locked in a bitter campaign that is a rehash of the 2002 GOP contest in which Bridgewater bested Swallow in the Republican convention only to lose to him in the primary.

Swallow lost the general election to Matheson by about 1,900 votes, and national Republicans are sure to target the heavily GOP seat again.

Matheson is sitting on a fat campaign war chest while Bridgewater and Swallow drain their funds for the primary.

According to the poll, the Bridgewater-Swallow race was too close to call, with a full 31 percent of the 303 surveyed voters saying they had yet to decide whom they were going to back.

In the 3rd district, the same poll found Rep. Chris Cannon (R) in good shape heading into the primary, despite a spirited challenge by former state lawmaker Matt Throckmorton.

In a race where immigration has become a touchy subject, the four-term Congressman led 44 percent to 23 percent.

The winner will face Democrat Beau Babka in November.

Both polls were conducted June 14-17 by Salt Lake City-based Dan Jones & Associates on behalf of the Deseret Morning News and KSL-TV and had a high 5.5 percent error margin.

The firm had previously done polling for Bridgewater.

In a serious turn of events late Monday, the Justice Department announced that it would be on hand to monitor the primary and ensure the Voting Rights Act of 1965 is upheld.

The decision comes on the heels of charges that a Cannon aide encouraged illegal immigrants to donate to Cannon’s campaign and promises by anti-immigration groups that they would work to ensure that only U.S. citizens vote today — something Latino groups have charged is tantamount to voter intimidation.