A conservative challenge to the president's health care law has the government teetering on the brink of a partial shutdown.

Now it's the Senate's move on must-do legislation to keep the government open past midnight on Monday.

The Democratic-led Senate is expected to reject the latest effort from House Republicans to use the measure to undermine President Barack Obama's health care law.

Congress was closed Sunday, after a post-midnight vote in the GOP-run House to delay parts of the new health care law and repeal a tax on medical devices as the price for avoiding a shutdown.

The Senate is set to convene Monday afternoon, just hours before the shutdown deadline. Majority Democrats promise they will kill the House Republican bill.