WASHINGTON – Already scrambling to steady a struggling campaign, Republican Mitt Romney confronted a new headache Monday after a video surfaced showing him telling wealthy donors that almost half of all Americans “believe they are victims” entitled to extensive government support.

Romney added that as a candidate for the White House, “my job is not to worry about those people.”

President Obama’s campaign quickly seized on the video, obtained by the magazine Mother Jones and made public on a day that Romney’s campaign conceded it needed a change in campaign strategy to gain momentum in the presidential race.

“There are 47 percent of the people who will vote for the president no matter what,” Romney is shown saying in a video posted online by the magazine. “There are 47 percent who are with him, who are dependent upon government, who believe that they are victims, who believe that government has a responsibility to care for them, who believe that they are entitled to health care, to food, to housing, to you name it.”

“Forty-seven percent of Americans pay no income tax,” Romney said.

Romney said his role “is not to worry about those people. I’ll never convince them they should take personal responsibility and care for their lives.”

Romney’s campaign did not dispute the authenticity of the video, instead releasing a statement seeking to clarify his remarks.

“Mitt Romney wants to help all Americans struggling in the Obama economy,” spokeswoman Gail Gitcho said. “He is concerned about the growing number of people who are dependent on the federal government.”

About 46 percent of Americans owed no federal income tax in 2011, although many of them paid other forms of taxes. More than 16 million elderly Americans avoid federal income taxes solely because of tax breaks that apply only to seniors, according to the nonpartisan Tax Policy Center.

Obama’s campaign called the video “shocking.”

“It’s hard to serve as president for all Americans when you’ve disdainfully written off half the nation,” Obama campaign manager Jim Messina said in a statement.

The remarks came at a closed-door fundraiser that Mother Jones reported occurred after Romney had clinched the GOP nomination on May 29. To protect the identity of the person who provided the remarks, Mother Jones blurred out the video and did not provide the date or location of the fundraiser

Many of the Americans who owe no income tax are reprieved because basic exemptions — such as the “standard deduction” — took their taxable income below the cutoff levels. The other half rely mainly on a variety of tax breaks, such as the credit that helps offset child care costs. These Americans range from the very poor to solidly middle-class families with jobs and homes.