Opinion polls show many voters are unhappy with the healthcare overhaul amid high unemployment and a still-sluggish economy, and could punish Obama's Democratic Party in mid-term congressional elections in November.
In his speech, Obama reiterated his message that the plan is part of his program to boost the economy and employment.
I want you to know we are working every single day to spur job creation and to turn this economy around, Obama told a crowd of some 2,500 people in Maine.
That's why we worked so hard over the last year to lift one of the biggest burdens facing middle-class families and small business owners, and that is the crushing cost of healthcare right here in America, he said to applause.
The 35 percent tax credit for small businesses, available from the start of 2010, is part of a $940 billion package of changes to the $2.5 trillion healthcare industry that represents the largest U.S. social policy shake-up in decades.
The White House said the credit, which rises to 50 percent of healthcare premiums in 2014 to help offset higher costs, would save small businesses $40 billion by 2019, according to estimates by the non-partisan Congressional Budget Office.
Obama urged Americans to see what benefits they experience from the new law before they judge it.
It's been a week, folks, he said. So before we find out if people like health care reform, we should wait to see what happens when we actually put it into place.
Democrats, who control both the House of Representatives and the U.S. Senate, passed the healthcare legislation without a single Republican vote.
Republicans hope they can turn the issue into a vote-winner. Polls show a majority of the country fear the reform will cost too much and invite unwelcome government intrusion into their lives.
The timing couldn't be worse for a bill that will make it even harder to create private-sector jobs, and harder for small businesses to comply with ... a thicket of new rules, said Senate Republican leader Mitch McConnell.
Obama aimed squarely at insurance companies and rival Republicans in praising the healthcare bill's passage as a victory over special interests and misinformation.
There's been a lot of misinformation spread about health reform. There's been a lot of fear-mongering, a lot of overheated rhetoric, he said.
You turned on the news, you'd see that those same folks who were hollering about it before it passed, they're still hollering about how the world will end because we passed this bill.
Obama, who noted that ideas from Maine's Republican Senator Olympia Snowe had been included in the law, repeated his challenge to Republicans to go for it if they wanted to make repealing it a strategy to win votes in November.
If they want to have a fight, I welcome that fight, because I don't believe the American people are going to put the insurance industry back in the driver's seat, he said.
A Gallup poll released on Thursday showed registered voters prefer the Republican to the Democratic candidate in their districts by 47 percent to 44 percent in the mid-term congressional elections. It was the first time Republicans have led in 2010 election preferences since Gallup began such weekly tracking last month.
The poll results came after the House passed the healthcare legislation on March 21. Obama later signed it into law.
The shift toward Republicans raises the possibility that the healthcare bill had a slightly negative impact on the Democrats' political fortunes in the short run, Gallup said in a statement.
Some big U.S. businesses have also started to tally up the financial hit they say they will take because of the healthcare law. Corporate America says the law raises their taxes, but the White House says it merely closes a loophole.