A new poll finds most Americans oppose GOP efforts to defund Obamacare.

A CNBC All-America Economic Survey released Monday finds 44 percent generally oppose defunding President Obama's signature healthcare reform law, with 38 percent in support.

When respondents are asked about the possibility of a government shutdown or default, opposition to defunding Obamacare rises to 59 percent, with 19 percent in favor.

The poll comes days after the GOP-controlled House passed a spending bill to keep government funded through mid-December, but which cuts blocks funds for healthcare reform.

The measure is likely dead on arrival in the Democratic Senate, and Obama has vowed to veto any bill that cuts funding for the health care law, raising the threat of a shutdown.

Congress must pass a spending bill to avert a shutdown on Oct. 1 and must raise the nation’s borrowing limit weeks later to avoid a default.

The poll finds Republicans generally in favor of defunding Obamacare by a 51-to-36 split. But that support loses ground when GOP voters are asked about a possible shutdown or default. In those scenarios, Republican oppose defunding by 48-36.

The poll has a margin of error of 3.4 percentage points.