Here comes the early Republican debate...

Four Republican presidential candidates are set to take the stage for the fifth in a series of lower-tier GOP debates.

Sen. Lindsey Graham (R-South Carolina), former Arkansas Gov. Mike Huckabee (R), former Sen. Rick Santorum (R-Pennsylvania), and former New York Gov. George Pataki (R) will participate in the early debate, which airs before the main-stage affair later in the night.

The four candidates did not meet the average 3.5% support nationally or 4% support in Iowa or New Hampshire to qualify for the main debate. But they did garner the 1% support necessary to qualify for the earlier so-called "undercard" contest.

Graham and Pataki did not qualify for the previous undercard debate.

Coverage of the early debate begins at 6:30 p.m. ET. Check back here for updates.