Stephen Hess is a Presidential Scholar at the Brookings Institution in Washington.

STEPHEN HESS:"It's a big deal. How big a deal you have to measure piece by piece but clearly it is the first major change in our health care system since nineteen sixty-five so that's a long time coming."

Mister Hess says the success of Barack Obama's presidency largely depended upon this vote.

STEPHEN HESS:"This is a very great victory for President Obama. This was his first year in office and in many ways he really staked his whole four-year presidency on the success in this vote on healthcare."

However, the new law is also considered a political risk. Most Democrats in Congress supported the measure. But all the Republicans opposed it. Opinion studies in recent days show the public is generally divided on the new law. A USA Today-Gallup poll shows a small majority believe the new health care plan is a good thing.

The health care debate also fueled the rise of the so-called Tea Party movement. The loosely organized group of activists opposed the health care plan as too much government involvement in the economy.

Congressional Democrats have been the targets of threats and destructive acts following the health care vote. House Majority Leader Steny Hoyer says at least ten members of Congress have received threats to themselves or their family members in recent days.

Republicans have promised to make the health care reform law a major issue in mid-term Congressional elections in November. Their goal is to defeat Democrats who supported the measure and then repeal, or cancel, the law. Republican Senator John McCain spoke to ABC News.