Unions have been energized by the 2006 election, which produced a Democratic-controlled Congress, and by the approaching end of the administration of Republican President George W. Bush, who fought their key initiatives as the Iraq war hurt his popularity, experts say.
''The labor movement is in a powerful position now,'' said Gordon Lafer, labor expert at the University of Oregon.
''There's a large number of people who are very angry and very highly motivated,'' he said.
The Democratic presidential contenders, who court unions far more than do business-oriented Republicans, are vying to win labor's backing in the November 2008 election.
Sens Hillary Rodham Clinton, Barack Obama, Joseph Biden and Chris Dodd, former Sen John Edwards, Rep Dennis Kucinich and New Mexico Gov Bill Richardson have been talking recently to unions, including the AFL-CIO federation, fire fighters and the International Association of Machinists.
''Labor is on the offense now, so you hear some of the presidential candidates really talking up labor issues more so than in 2004,'' said Peter Francia, author of ''The Future of Organized Labor in American Politics.'' Activists say labor lost ground under Bush in efforts to organize workers, improve workplace safety and curb outsourcing of jobs overseas.
A White House veto threat hangs over a top item on labor's agenda legislation to simplify organizing by letting workers form unions with signed cards rather than the current secret ballot which passed the US House of Representatives in March but faces opposition in the narrowly divided Senate.
NEVADA CONTEST Pro-labor Democrats say Nevada, a relatively strong union state slated to move up its primary to an early date, could boost labor's influence in the campaigns. Seventeen percent of Nevada workers are represented by unions, higher than the nation's 12 per cent rate, according to government statistics.
The US rate is far lower than in European Union countries, where union membership ranges from roughly 11 per cent in Portugal to 84 percent in Denmark.
''I am optimistic that we can elect a president who cares about working people,'' said Bruce Raynor, head of UNITE HERE, which represents 60,000 workers in Nevada.
''Income inequality and health care and retirement insecurity and job insecurity are so pronounced in the minds of most Americans,'' Raynor said. ''The candidates are more attuned to the interests of workers than in many years.'' At the 10 million-member AFL-CIO, ''There is the greatest level of enthusiasm heading into '08 than I've seen in many, many years,'' said political director Karen Ackerman.
Organized labor is planning candidate and issue forums and drives to register voters and get them to the polls. Some make heavy campaign contributions and influential endorsements, and political strategists consider unions expert at mobilizing volunteers.
US union membership has declined for decades, but its influence is large, experts say. One in four voters in 2004 belonged to a union household.
By a 2-to-1 margin, unionized voters backed Democrat John Kerry's failed bid for the presidency in 2004, when US organized labor spent heavily in an effort to unseat Bush.
But for 2008, even opponents say unions have a stronger hand.
''Is there a better chance that a Democrat gets elected next time? Sure, probably, I think that's fair to say,'' said Doug Stafford of the National Right to Work Committee. ''It's hard to look at the poll numbers of the current administration and say anything else.'' Reuters DS DB1843