As Republicans plot strategy on Obamacare, a key disagreement keeps arising in GOP circles as the party debates whether to leverage the specter of a government shutdown in an attempt to force President Obama to abandon his signature health care overhaul: Who would voters blame for a government shutdown?

Would they fault the Republicans for being the first to threaten to withhold their critical votes for a spending bill to keep the government running beyond the Sept. 30 end of fiscal 2013, unless Democrats agree to defund the Affordable Care Act, which is already on the books?