Public support for repealing last year's sweeping health care reform law has fallen dramatically in the aftermath of a shooting rampage in Arizona that critically injured a Democratic congresswoman.

Only one in four Americans said they support full repeal of the reforms, according to a newly-released Associated Press-GfK poll, and 30 percent strongly opposed the law, the lowest figure since September 2009.

The drop is particularly notable among Republicans. Forty-nine percent said they're against the law, down considerably from 61 percent after the elections.

A survey by Gallup found that on Jan. 7, one day before the shootings, Americans supported repeal by a margin of 46 to 40 percent.

But the nation remains deeply divided over the law. Overall, 40 percent in the AP-GfK poll said they support it, while 41 percent were less than pleased, some of whom thought it doesn't go far enough.

The shift in public opinion doesn't appear likely to sway the outcome of a repeal vote slated for this week. The GOP bill, titled "Repealing the Job-Killing Health Care Law Act," is expected to pass comfortably in the House, where Republicans hold a 241-173 majority.

But it's likely to hit a brick wall in the Democratic-controlled Senate, and President Barack Obama has threatened to veto it if it passes.

Rolling back the measure, enacted last March after a year of bitter controversy and drama, was a dominant Republican campaign pledge in the November midterm elections.

The Republican repeal measure will add $230 billion to the deficit by 2021, according to the nonpartisan Congressional Budget Office.

The reforms ban insurance companies from discriminating against sick patients and those with pre-existing conditions, and employs federal subsidies and an individual mandate to expand coverage. The CBO projects it will cover 32 million Americans by 2019 and reduce the deficit.