Cobun has offered an amendment to strike the measure from the tax extenders bill.
The "Cornhusker kickback" provided increased Medicaid funding to Nebraska and was included in the Senate’s healthcare bill to ensure Sen. Ben Nelson’s (D-Neb.) support.
The Nebraska provision was criticized as a backroom deal by Republicans and later removed at Nelson's request.
The California provision was included in the House-passed version of the tax extenders bill at the request of Rep. Sam Farr (D-Calif.).
Farr and Sen. Dianne Feinstein (D-Calif.) have long-backed stand-alone legislation to increase Medicare reimbursement rates for California counties, and Farr's office dismissed Coburn's amendment as election-year politics.
Though Senate Republicans are seizing on Farr's measure as an earmark, the provision has support from some Golden State Republicans in the House and Gov. Arnold Schwarzenegger (R).
The provision "would make Medicare payments for these counties more equitable, and the Governor supports California receiving its fair share from the federal government," said Rachel Arrezola, a spokeswoman for the governor.
Six GOP House members, including Reps. Duncan Hunter, Dana Rohrabacher and Brian Bilbray, have joined with Democrats in either co-sponsoring Farr's bill or signing letters in support of the increased doctor payments.
Farr spokesman Tom Mentzer said California counties have waited 10 years to get the legislation.
“You have seniors who cannot find a Medicare physician,” he added.
Mentzer acknowledged there are about 15 other states with areas that have rising healthcare costs due to growth yet still get lower payments because they're considered rural by Medicare formulas. But he said California has as many short-changed areas as the rest of the country combined.
The increase in payments for California counties could serve as a “pilot program” to spur Medicare administrators to fix payment formulas for other states, Mentzer said.