Joann Marshall of the American Association of Retired Persons joins opponents of Wisconsin Gov. Scott Walker's budget repair bill for protests inside and outside the Wisconsin State Capitol Building in Madison on Saturday. (John Hart/Wisconsin State Journal/Associated Press)

Rallies were held across the United States on Saturday to support thousands of protesters holding steady at the Wisconsin Capitol building in their fight against Republican-backed legislation aimed at weakening unions.

Union supporters organized rallies from New York to Washington state in a show of solidarity as the demonstration in Madison entered its 12th straight day — and attracted its largest crowd of more than about 70,000 people.

Hundreds of people banged on drums and screamed into bullhorns inside the Capitol, while the others braved the sub-freezing temperatures and a heavy snowfall for a rally outside.

"I want to thank you for coming out here today to exercise those pesky First Amendment rights," actor Bradley Whitford told his hometown crowd. "This governor has to understand Wisconsin is a stubborn constituency. We fish through ice!"

The Wisconsin native, who has had starring roles in television's The West Wing and the Adam Sandler movie Billy Madison, said he was taking the governor's efforts personally.

Republican Gov. Scott Walker has introduced a bill that would require public sector workers to give more to their pensions and health care. Other provisions in the measure would strip almost all public workers, from librarians to snowplow drivers, of their right to collectively bargain on their benefits and work conditions.

Several thousand people gathered in Columbus, Ohio, where lawmakers are considering a similar bill. Large crowds of teachers, firefighters and public workers also gathered for rallies in other capital cities including Topeka, Kan.; Harrisburg, Pa.; and Olympia, Wash.

"Wisconsin is opening up people's eyes a little bit, so I think that the move is to try to get people more involved in their unions and create a stronger front so that if something happens here, we are prepared," said 40-year-old teacher Jay Van Loenen, who attended a rally in Denver that attracted about 1,000 people.

Madison Police spokesman Joel DeSpain said he didn't have a firm estimate on the Wisconsin capital's crowd, but said it was larger than last weekend when nearly 70,000 people descended on the Capitol.