U.S. President Barack Obama has encouraged Democratic members of the Senate to "continue forward" on a historic overhaul of the U.S. health care system.

The president made a rare weekend visit Sunday to the Capitol to urge Senators to work through their differences and pass health care reform, his top domestic priority. The White House says President Obama thanked Senators for their work so far and reiterated the importance of bringing affordable coverage to the uninsured, and keeping costs down for families and small businesses.

Senate Democratic leaders are working with moderate members of their party to put together the 60 votes needed to pass a bill. The leaders are focusing on a compromise over a provision in the legislation to create a government-backed insurance plan that would compete with private insurers.

Some Democratic senators have voiced opposition to such a plan. Both the White House and Democratic leaders in Congress want a bill to pass before year's end. Sixty votes are needed to overcome stalling tactics by Republicans in the 100-member Senate.

Health care reform, which has already passed the House of Representatives, is designed to provide coverage to about 30 million Americans who lack it. It also aims to limit the growth of spending on health care.

Some information for this report was provided by AP.