ABC's Isobel Markham reports:

With the threat of a govenrment shutdown looming, Rep. Tom Graves defended his effort to defund President Obama's signature health care law on "This Week" Sunday.

"We are united around a very simple goal, and that is keeping the government open while protecting our constituents from the harmful effects of Obamacare," Graves said. "We have eight days to do that."

The House voted on Friday 230-189 along party lines to pass Graves' bill - his first as a House member - that would extend funding for government operations until mid-December, while defunding the Affordable Care Act, passed into law in 2010. The defunding bill was put forward in the House by Graves, who has taken up the fight led in the Senate by freshman Tea Party Senators Ted Cruz, R-Tex. and Mike Lee, R-Utah to pull the plug on funding for Obamacare.

Friday's continuing resolution now heads to the Democratic-controlled Senate, where it will likely be rejected. Tea Party efforts to drum up support in the Senate for defunding Obamacare has yielded lackluster results, with many leading Republicans openly acknowledging the futility of the effort.

On "This Week" Sunday, House budget committee ranking member Rep. Chris Van Hollen, D-Md., dismissed the efforts to defund President Obama's health care law.

"There's a reason Republican senators like Senator McCain and others are saying this is absolutely insane," Van Hollen said. "They're going to shut down the government if they can't deny health care to millions of Americans."

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An ABC News/Washington Post poll this week showed that 52 percent are opposed to the law and only 11 percent believe Obamacare will improve their health care. Van Hollen puts this down to confusion surrounding the law, stirred up by Republicans.

""I'm not surprised that there's a lot of confusion. These guys have been running around the country demagoguing, scare mongering on this issue," Van Hollen said. "They're not afraid that it's going to be unsuccessful, they're afraid it's going to be successful and all of that misinformation will be shown to be a fraud."

"Whenever there's a flood these days, you guys in the Republican Party say that's Obamacare," Van Hollen added.

And Van Hollen maintained that support for the health care law was made clear in the 2012 presidential election.

"The biggest poll we had on this was the last election," Van Hollen said. "President Obama said that she was going to implement the Affordable Care Act and Mitt Romney said he was going to defund it. And the president won on that issue and other issues."

Graves responded that since the election, the Obama administration has made changes to the law, including delaying implementation of certain portions for businesses.

"Something very important has happened since the president did win the election and that he himself has amended, delayed, or repealed 19 components of his very own law," Graves said.

President Obama said Thursday he would veto any government funding bill that didn't include ACA funding. Failure to reach a resolution could result in government shutdown on October 1.

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