By Tim Reid
SALEM, Virginia (Reuters) - Republican Mitt Romney stepped up his criticism on Tuesday of President Barack Obama's signature domestic policy achievement, saying if the U.S. Supreme Court does not overturn the 2010 healthcare overhaul when it decides its fate this week he would dump it if elected in November.
Eager to change the subject back to Obama's economic stewardship after nearly two difficult weeks focusing on immigration, Romney accused Obama of taking his eye off the ball when he pushed the healthcare measure through Congress in 2010.
"Instead of focusing on the big issue, the economy, he focused on his healthcare reform, called Obamacare," Romney, set to challenge the Democratic president in the November 6 election, told a crowd at a machinery manufacturer in Salem, Virginia.
At the mention of "Obamacare" - the derisive nickname critics have given the law - the crowd erupted in boos.
The Supreme Court is scheduled on Thursday to rule on a legal challenge posed against the law by 26 of the 50 U.S. states and a small business trade group that argued the measure violates the U.S. Constitution.
Romney said if the high court justices deem the law unconstitutional, "then the first three and a half years of the president's term will have been wasted on something that has not helped the American people."
"If it stands, we are going to get rid of Obamacare and I'm going to stop it on day one," Romney added.
The 2010 law, which constitutes the U.S. healthcare system's biggest overhaul in nearly 50 years, sought to provide health insurance to more than 30 million previously uninsured Americans and to slow down soaring medical costs. Critics say it meddles in the lives of individuals and in the business of the states.
The justices could uphold the law, strike down certain provisions or overturn the whole thing.
Romney enacted healthcare changes as governor of Massachusetts that bore similarities to the law Obama signed. But Romney argues that the federal law is killing jobs.
Romney's aides on Tuesday circulated a report, first published last year, in which a medical device manufacturer asserted that the 2010 law would cost the company so much in additional overhead costs that it might have to ship thousands of jobs overseas.
Romney in recent days has been tied up with the issue of immigration and has struggled to lay out an immigration plan.
He appears to have been caught flat footed by Obama's announcement on June 15 that hundreds of thousands of illegal immigrants who were brought into the United States as children could be able to avoid deportation and get work permits. Most illegal immigrants in the United States are Hispanics.
In response, Romney accused Obama of political motivation in making the policy change, but declined to say he would repeal it if elected.
Romney also was cautious in reacting to Monday's Supreme Court ruling upholding a portion of Arizona's state crackdown on illegal immigrants while striking down other parts of the law.
Looking more comfortable on Tuesday, Romney stood in front of a banner stating, "Putting Jobs First." "Do you think Obamacare is working just fine to get the American people back to work?" he asked people in the crowd. "No!" they yelled back.
Romney's own record on job creation was challenged by Vice President Joe Biden, who accused him of devastating entire communities as a private equity executive in the 1980s and 1990s who shipped U.S. jobs abroad.
"Like so many other things the governor talks about, there is a huge disconnect between what he says and what he means and what he's done," Biden told supporters in Iowa, referring to Romney's time as head of the investment firm Bain Capital.
Citing a Washington Post report, Biden said Romney's former firm helped move American jobs overseas.
"They made a great deal of money facilitating this outsourcing and offshoring American jobs. Yeah, they made a lot of money. But in the process they devastated - they devastated - whole American communities," he said.
Obama and Romney are running close in opinion polls, with a PPP survey in the battleground state of Ohio showing the president with a lead of 3 percentage points, down from 7 percentage points a month ago.
(Additional reporting by Laura MacInnis in Washington; Editing by Will Dunham)