Organized labor's early flirtation with Occupy Wall Street is starting to get serious.

Union leaders, who were initially cautious in embracing the Occupy movement, have in recent weeks showered the protesters with help — tents, air mattresses, propane heaters and tons of food.

The protesters, for their part, have joined in union marches and picket lines across the nation. About 100 protesters from Occupy Wall Street are expected to join a Teamsters picket line at the Sotheby's auction house in New York on Wednesday night to back the union in a bitter contract fight.

Labor unions, marveling at how the protesters have fired up the public on traditional labor issues like income inequality, are also starting to embrace some of the bold tactics and social media skills of the Occupy movement.

Last Wednesday, a union transit worker and a retired Teamster were arrested for civil disobedience inside Sotheby's after sneaking through the entrance to harangue those attending an auction — echoing the lunchtime ruckus that Occupy Wall Street protesters caused weeks earlier at two well-known Manhattan restaurants owned by Danny Meyer, a Sotheby's board member. The art-auction house locked out 43 Teamster art handlers on July 29, after the union balked at its demands for sizable concessions.

Organized labor's public-relations staff is also using Twitter, Tumblr and other social media much more aggressively after seeing how the Occupy protesters have used those services to mobilize support by immediately transmitting photos and videos of marches, tear-gassing and arrests.

The Teamsters, for example, have beefed up their daily blog and posted many photos of their battles with BMW, US Foods and Sotheby's on Facebook and Twitter.

"The Occupy movement has changed unions," said Stuart Appelbaum, the president of the Retail, Wholesale and Department Store Union. "You're seeing a lot more unions wanting to be aggressive in their messaging and their activity. You'll see more unions on the street, wanting to tap into the energy of Occupy Wall Street."

Organized labor is also seizing on the simplicity of the Occupy movement's message, which criticizes the great wealth of the top 1 percent of Americans compared with the economic struggles of much of the bottom 99 percent.

A memo that the AFL-CIO sent out last week recommended that unions use the Occupy message about inequality and the 99 percent far more in their communications with members, employers and voters.

Indeed, as part of its contract battle with Verizon, the communications workers' union has began asserting in its picket signs that Verizon and its highly paid chief executive are part of the 1 percent, while the Verizon workers who face demands for concessions are part of the 99 percent.

Over the last month, unions have provided extensive support to Occupy protesters around the country, from items such as lanterns and rain ponchos to cash donations.

The National Nurses United is providing staff members for first-aid tables at many encampments, while the AFL-CIO's headquarters two blocks from the White House is providing shower facilities for the protesters occupying McPherson Square, 300 yards to the east.

"Young people started this movement, but they can't finish it," said Arthur Brown, a mental-health worker who is one of the founders of Occupy Buffalo. "They don't have the capacity or the experience to finish it. We really need the working class and union folks, the older folks, the activists from the '60s, '70s and '80s, to help make this a full-fledged movement that will change the political landscape of America."