COLUMBIA, S.C. -- Republican Gov. Mark Sanford's took the unusual step Monday of endorsing his former chief of staff against a GOP incumbent in a state Senate race.

But some in state politics are just as surprised Sanford hasn't fielded a much longer string of allies to take on fellow Republican lawmakers he thinks are stopping his legislative agenda.

Sanford visited Beaufort and Hilton Head Island on Monday to endorse state Senate candidate Tom Davis. The lawyer is a longtime adviser, serving as Sanford's chief of staff, top counsel and chief lobbyist as well as on his gubernatorial campaigns.

Davis is running against Sen. Catherine Ceips, who won the seat last June in a special election after defeating Sanford's favored candidate in the primary.

The governor also has endorsed Tim Scott, who is running for an open House seat against two primary opponents, and Mick Mulvaney, who is running for an open Senate seat with no GOP opposition.

Sanford spokesman Joel Sawyer said the governor has not decided if he will make any more endorsements.

Any primary endorsement is rare for governors, said Dave Woodard, a Clemson University political scientist. At that level, "if there's one cardinal rule in politics, it's stay out of primaries."

But none of the endorsements so far have the makings of the much talked about Sanford "hit list" for Republican incumbents that prompted legislators to redouble their fundraising efforts this year. The governor has always denied he had anything to do with any kind of hit list.

Woodard said he actually got a copy of one version making the political rounds. The names he saw made sense because they were Republican lawmakers who have clashed before with Sanford.

State GOP Chairman Katon Dawson said rumors of the list were overblown.

"I always know a lot of people invoke Mark Sanford's name and he really doesn't have a lot of time to the things he's accused of doing," Dawson said. "A lot of people spend Mark Sanford's political capital when they just aren't authorized to do it."

Sanford does bring some of the accusations on himself by raising money and actively supporting groups that say they will target incumbent Republicans, including the Club for Growth, said Terry Sullivan, a Columbia political consultant.

Republican incumbents are facing about as much primary competition this year as they usually do. In the House, there are 14 primaries involving GOP incumbents; there are eight in the Senate.

Democratic Senate and House incumbents are facing more challengers than usual, with 13 primary contests in the House and six in the Senate.