Sen. Coburn Fighting A Straw Man
In fact, it is common knowledge, which is why those pushing to defund Obamacare are also pushing to fund the government. In short, Sen. Coburn has constructed a straw man argument to fight his fellow conservatives, thereby preserving Obamacare.
Defunding Obamacare means attaching a legislative rider to a “must pass” bill (debt limit, annual spending bill, etc.) that 1) prohibits any funds from being spent on any activities to implement or enforce Obamacare; 2) rescinds any unspent balances that have already been appropriated for implementation; and 3) turns off the exchange subsidy and new Medicaid spending that are on auto-pilot.
Perhaps Sen. Coburn just misunderstood the strategy, which has always been to actively defund Obamacare, not shut down the government.