A little-known Republican congressional candidate in Southern California has received $137,000 in campaign donations from Democrats from across the U.S. ahead of Tuesday's primary.

But John Gabbard -- a small business owner and Marine Corps veteran -- rejected the Democrats' help Friday, accusing the party of “bringing its classic unethical tricks from the swamp in Washington to the shores of Orange County.”

The Dems' backing of the GOP's Gabbard in California's 48th Congressional District seems to be part of an unorthodox strategy --- not to help Gabbard, but to ultimately help the Dems get one of their own candidates to emerge from Tuesday's primary and appear on the November ballot.

It's part of some $5.4 million that the Democratic Congressional Campaign Committee has spent on congressional races in Orange County in recent weeks, the Orange County Register reported.

Under California primary rules, the top two vote-getters Tuesday, regardless of party, will face each other in November. So if two Republicans top the field, the Democrats would be shut out of the general election.

That GOP shutout is likely to happen in the 48th District, because two of the candidates are well-known former Orange County GOP Chairman Scott Baugh and incumbent U.S. Rep. Dana Rohrabacher, the Register reported.

"The [Democratic Congressional Campaign Committee] machine is bringing its classic unethical tricks from the swamp in Washington to the shores of Orange County." — John Gabbard, GOP candidate seeking a U.S. House seat

So the Democrats' best hope of getting one of their own -- either businessman Harley Rouda or stem-cell biologist Hans Keirstead -- to finish in the top two may be to back Gabbard, and hope he siphons enough votes away from Baugh or Roherabacher to eliminate one of them and help a Democrat advance.

Robocalls and radio ads funded by Democratic organizations have lavished praise on Gabbard’s wartime service, touting him as a man who has “traveled the world keeping America safe” and who “evacuated hundreds of Americans threatened during an African coup.”

At least one politcal watcher says Democrats are making a big mistake with their opposite-party financing.

"That's the kind of game plan that really turns voters off. That money would be so much better spent just on get-out-the-vote efforts." — Jodi Balma, political science professor, Fullerton College

"That's the kind of game plan that really turns voters off," Jodi Balma, a political science professor at Fullerton College, told the Register. "That money would be so much better spent just on get-out-the-vote efforts."

Will the Democrats' plan work? Orange County voters will find out next week.

Click here for more from the Orange County Register.