National Democrats have spent $137,000 in recent days promoting an Orange County Republican congressional candidate in a complex strategy aimed at helping a Democrat survive the June 5 primary to make the November ballot.

The radio ads and robocalls supporting John Gabbard, a GOP candidate in the crowded 48th Congressional District contest, seem to be part of an unorthodox tactic to siphon votes away from the race’s top leading Republicans, incumbent Congressman Dana Rohrabacher and former Orange County GOP Chairman Scott Baugh.

Due to California’s jungle primary system, which advances the top two vote-getters regardless of party, it’s possible both Rohrabacher and Baugh could make it to November, leaving Democrats without a candidate in the race. The leading Democrats in the race for the 48th are businessman Harley Rouda and stem-cell biologist Hans Keirstead.

Fearing an all-GOP ballot, the Democratic Congressional Campaign Committee (DCCC) has spent $5.4 million in three Orange County congressional races in recent weeks, including some money that, on its face, might help Republican candidates. Until this week, the DCCC’s strategy has been to attack the contests’ second and third-place Republicans, including $1.7 million opposing Baugh, in an effort to consolidate GOP votes around one top candidate.

The Democrat-funded ad lauds Gabbard as a “conservative champion” and Marine veteran who “traveled the world keeping America safe,” and who “evacuated hundreds of Americans threatened during an African coup.”

Gabbard, a small business owner, issued a statement on Friday rejecting the Democratic support.

“The DCCC machine is bringing its classic unethical tricks from the swamp in Washington to the shores of Orange County,” Gabbard said.

A DCCC spokesman declined to comment on the independent expenditures.

Jodi Balma, a political science professor at Fullerton College, said she couldn’t recall another instance in which one political party paid for ads to support a candidate from another party.

“That’s the kind of game plan that really turns voters off,” Balma said. “That money would be so much better spent just on get-out-the-vote efforts.”

In 1994, in another case of political gamesmanship, local Republicans promoted a Democratic candidate to split the left’s vote.

After that election, Rohrabacher’s wife and Baugh were both charged criminally for a ploy to recruit a decoy Democrat candidate in a race for state Assembly. Rohrabacher’s wife pled guilty while the charges against Baugh were dropped.

Another political action committee connected with California’s Service Employees International Union also spent $39,000 supporting Gabbard on Wednesday and Thursday.