Chanting "Kill the bill," thousands of conservatives rallied at the Capitol on Thursday against the Democrats' health care overhaul plan.

The campaign-style event kicked off a daylong, Republican protest against the legislation.

"This bill is the greatest threat to freedom that I have seen," House Republican leader John Boehner of Ohio told the crowd gathered on the lawn near the West Front of the Capitol.

Said Rep. Steve King, R-Iowa: "We're not going to leave this Hill until we kill this bill."

Among the signs in the crowd was one reading, "Waterboard Congress," and another saying, "Vote no to government-run health care." The crowd included a significant number of older Americans.

Some conservatives oppose increased government involvement as the first step on a slippery slope to "socialized" medicine, a term they use to denigrate other countries' health care systems, and insist on rugged American individualism, in which people should be responsible for their own health care.

In addition, millions of Americans get health care from their employers and are reluctant to see any tinkering with that system.

Hoyer's prediction
However inside the Capitol, legislative action continued in both chambers.

House Majority Leader Steny Hoyer predicted the bill will be passed in the House on Saturday. It is aimed at extending coverage to tens of millions of uninsured Americans and banning the medical insurance industry from turning people away. The Senate is working on its own bill, which will have to be reconciled with the House bill for final legislation.