CNN

Tea Party activists hit the Hill, arrested outside Pelosi's office.

Washington (CNN) - GOP leaders and thousands of Tea Party movement protesters gathered on Capitol Hill Thursday to call House Democrats' health care reform bill a full-blown government takeover of the nation' health care system.

"My colleagues and I last week were wracking our brains trying to figure out what could we do, because quite simply Republicans don't have the votes to kill this bill," Rep. Michele Bachmann of Minnesota told the crowd. "Every lever of power is controlled by one party now in DC. We tried to figure out what we could do. We knew that we were limited. But what we knew was unlimited was the voice of persuasion of the American people, and that's why you are here today with your voice of persuasion.

"....Let me assure you your efforts to stop this bill are being heard loud and clear. And I will guarantee you that we are committed to making sure that not one Republican will vote for this bill."

Actor John Ratzenberger, known partly for his role as Cliff Clavin in the 1980s sitcom "Cheers," slammed the Democratic bill as a form of socialism.

"These are Woodstock Democrats," he said at the rally. "We have to remember where their philosophy comes from. It doesn't come from America. It comes from overseas. It comes from socialism. And socialism is a philosophy of failure."

Police later arrested 12 protesters outside Pelosi's office for unlawful entry or disorderly conduct, according to Capitol Hill police spokeswoman Sgt. Kimberly Schneider.

Democrats have rejected an alternative $60 billion House GOP reform plan as inadequate for meeting the goals of expanding health coverage to most of the nation's 46 million uninsured while bringing down costs and ending controversial industry practices such as denying coverage for pre-existing conditions.