Former Arkansas Gov. Mike Huckabee (R) is heading to North Carolina to campaign for Rev. Mark Harris (R), an underdog in the primary to face Sen. Kay HaganKay HaganPolitics is purple in North Carolina Democrats can win North Carolina just like Jimmy Carter did in 1976 North Carolina will be a big battleground state in 2020 MORE (D-N.C.).

Huckabee, who endorsed Harris earlier this year and is eyeing another presidential bid, will be in Raleigh this Saturday to help Harris boost his campaign coffers.

Harris, who led the successful push to ban gay marriage in North Carolina, is facing North Carolina House Speaker Thom Tillis (R) and Tea Party candidate Greg Brannon (R) in the race.

Tillis is the favorite of establishment Republicans. He's returning to D.C. for another Capitol Hill fundraiser next Monday. Sen. Richard BurrRichard Mauze BurrOvernight Energy: Chemical safety regulator's nomination at risk | Watchdog scolds Zinke on travel records | Keystone pipeline spills 210,000 gallons of oil Overnight Regulation: Senators unveil bipartisan gun background check bill | FCC rolls back media regs | Family leave credit added to tax bill | Senate confirms banking watchdog Collins ‘leaning against’ Trump EPA chemical nominee MORE (R-N.C.) will headline the event — it's at least the second time he's stepped in to help Tillis raise cash for his bid, though he hasn't officially endorsed him.

Establishment Republicans are hoping they can help push Tillis ahead of the other two candidates, ideally helping him win the 40 percent needed in his May 6 primary to avoid a costly mid-July runoff.

Recent polls have shown a mixed picture of the race. Harris's campaign released an internal poll that had Tillis at 33 percent support, Harris at 22 percent support and Brannon at 12 percent support, while public surveys from the automated Democratic firm Public Policy Polling have found a closer race, with none of the candidates rising above 20 percent.