Lech Walesa -- labor organizer, Nobel Prize winner, architect of a peaceful revolution ... and TV pitchman? The leader of Poland's Solidarity trade union has added to his list of causes the role of helping organized labor boost its ranks in this country through a 30-second commercial spot for the AFL-CIO. Picking up where actors Howard Hesseman and Jack Lemmon left off, Walesa urges Americans to "Say 'Union Yes.' " The commercial, which aired nationally on "Roseanne" and the Miami-Notre Dame football game last week, was filmed in Washington before Walesa's address to the AFL-CIO national convention two weeks ago. Walesa agreed to make the commercial before traveling to the United States for the convention and an address to a joint session of Congress. A spokesman for the AFL-CIO acknowledged that Walesa gives the two-year-old "Union Yes," campaign a little extra prestige compared with Hesseman, Lemmon and actor Edward James Olmos and actress Tyne Daly, who previously spoke for the organization. "What are we going to do for an encore after Walesa? That's a very good question," said Rex Hardesty of the labor organization. The commercial is an edited version of about 90 minutes of off-the-cuff remarks Walesa made in Polish during filming in the AFL-CIO's television studio. According to the commercial's English subtitles, Walesa says: "Thank you, America. You have inspired the world with the ideals of freedom, allowed trade unions to flourish and workers to have democracy on the job. Please continue your support for us in Poland, and support your unions in the United States." He says the slogan in English, pronouncing it, "Say oonion yes." The union said it has received congratulatory calls about the commercial from around the country and intends to keep airing it in several cities. Said Hardesty, "We've gotten a good response from counties that voted 63 percent for Reagan and Bush, so we must have done something right."